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Old February 16, 2020, 15:17   #1
BarnOwlLover
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Ideal Intermediate Round (Past, Present, Made Up)

This is a follow up to the High End Intermediate Round discussion. Here, I'm looking for opinions on what the best extant intermediate type round out there now, or if a round that never came to the fore should be revived for a second look, or if something new should be pursued as far as caliber, case size or both.

This goes to the reality that modern 5.56mm, 5.45mm or 7.63x39mm rounds are often limited to 300-400 yards or meters due to ballistics and such. This also ties in to something I read on The Firearm Blog about the USMC wanting to revise their training in the next couple of years to more simulate tactical shooting in combat, and to take advantage of modern optics that allow for easy engagement out to 500-600+yards/meters.

That alone in my mind would suggest the desire for a new round, possibly in between 5.56mm/7.62x39mm and .308 Win/7.62mm NATO in performance.

I know that some will argue why not just use 7.62mm NATO, or why didn't NATO use the .280 British round back when it was offered, and so on.

That's part of the point of this discussion, or if something newer or maybe obscure can fit the bill.
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Old February 17, 2020, 12:44   #2
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I have no idea what round would fit what you want. It seems over the years that many rounds have come along with the energy to perform their needed task as ammo but they don't fit what the military needs in their delivery.

The wars we fight change the military mind on what we need. When we fought in the jungles of Vietnam the 556 was good enough for many reasons. Yet when we fight at ranges longer like Afghanistan or Iraq they had to modify rifles with optics to hit at long distance. The 556 has how much energy at 600 yards, yet the enemy in Afghanistan was shooting 762×39 at the same range in a gun battle.

Like I said, I really don't have an answer because the question is much bigger than caliber alone.
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Old February 17, 2020, 15:42   #3
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I guess that I'm looking for the ideal general purpose rifle/LMG round that has much more ballsitic potential than 5.56mm or 7.62x39mm, and much better accuracy and stopping power at longer ranges, without having to up gun to .308/7.62mm NATO or above.

Also, the round has to be at least reasonably controllable in full auto for like CQB or where suppression fire is desirable.

I do agree with you that this isn't very easy to pin down, and most of us here aren't ammo experts or designers.

To complicate matters, when you look at rounds that were developed in the past, it gets more difficult as a lot of comparisons actually become apples to oranges, even within the same caliber of round.

Like say .280 British. It started out as a round that as specified, was superior to the 7.62x39 in terms of range and energy, but was still a reasonable full auto round. Then came the Mk1Z round that fired a heavy bullet at nearly 2600 fps. It replicated, to an extent, .308 Win/7.62mm NATO performance, but was also reputed to be damn near uncontrollable in the EM-2 rifle in full auto.

Here's a chart from The Firearms Blog on the recoil values of various ammo. Of note here is how the .276 Pedersen compares to 4 main variants of the .280 and the .270 British/.270 Enfield round:

https://www.thefirearmblog.com/blog/...oil-Energy.png

It's also like criticism of modern 7.62mm NATO loadings not being as accurate as hoped for at very long range (say beyond 800 yards/meters) unless match ammo is used because of bullet drift and such. Same actually happened in World War II where machine gunners and snipers preferred to use the M2 AP .30-06 Springfield round or the earlier M1 ball round. M2 ball tended to show less consistent and less precise accuracy than the M1 ball and M2 AP rounds did. Maybe if 7.62mm NATO used the same bullet design as the M1 .30-06 ball did, that issue might be resolved.

Rounds like say the PD-42 version of the .276 Pedersen and maybe 7.35mm Carcano probably have the ballistics I'm looking for as an ideal GP round. Problem is that both rounds are as long as the .308 Win/7.62mm NATO and 6.5mm Creedmoor (or slightly longer in the case of 7.35 Carcano). However, both rounds have slimmer shell casings than say .308 or .30-06 (base/rim diameter of .276 and 7.35 are nearly identical to 7.62x39, at .445-.45 inch, while .308 and .30-06 is between .47-.473, which the .280 British adopted during development) and are loaded to much lower pressures than the .30 high powered rounds.

Hence, it should in theory be more effective to load the rounds into shorter casings that can withstand such pressures, but be more compact.

Also some comments from a TFB writer and researcher here on a Forgotten Weapons post on a Pedersen PB rifle:

https://www.forgottenweapons.com/sho...-276-pedersen/

Caliber is also tricky. 6-7mm bullets tend to have very good ballistics in flight and with proper bullet design can cause severe wounds that can easily kill or at least incapacitate an adversary. 7-8mm bullets tend to be a bit heavier and have more frontal area, though often at some expense to ballistic coefficient. I'd like to avoid stubby bullets like used in 6.8 SPC or even 7.62x39 for ballistic considerations and the fact that such bullets tend to behave more like pistol rounds or round nose straight sided bullets (think 6.5mm Carcano) in tissue instead of what spitzer/boat-tailed bullet usually do.

That's why I also look at say the 6.25mm British round with interest, too. It fired a fairly heavy bullet with a very good BC and excellent penetrative abilities. Problem is that it was just a proof of concept round hastily made up to test the concept or the round. It used a .280 British shell casing, and if it made it to production, it probably would've adopted a shell casing similar to the .270 Enfield or a shortened Carcano or Pedersen casing. However, the round showed promise but was killed by the .22 caliber micro craze started by the .223 Remington that would form the basis ultimately for the 5.56mm NATO.
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Old February 17, 2020, 16:26   #4
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I don't know if you could ever get a golf bag approach to ballistics out of one gun and caliber. The British tried it but they went from an FAL to a bullpup design at the same time they converted calibers. The military designs either fight the last war or the next war so the change of gun and cartridge both is a dangerous step.

The M16 didn't have failures until it was put into service and the powder went from extruded to ball. So what will be the next cartridge gun combination? The 6.5 is said to be accurate as can be but will that still be true when the military sets the criteria for gun and caliber?

Say you want something in a semi auto with reach but not the kick of the 308. Getting a gas system to run on extruded powder may or may not be a problem but it looks like good accuracy is found with extruded powder. Ball powder works fine but I wonder with a different cartridge if you will have to trade off to get something that shoots long range and still runs good in a semi.

Guys I hunted with used a variety of calibers and all worked well if the shot was good. One guy, Mel, could drive tacks with his 6mm. Another fellow used a 250 savage and killed 18 bear in his lifetime of hunting. I saw him kill a running bear across the canyon with that 250 and the round exploded the heart when he hit it.

I don't have any idea how these rounds would work in a semi auto.
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Old February 17, 2020, 16:42   #5
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Okay, I'll play.

Let's say you want to keep the cartridge small enough to be able to use it in an M16/M4/AR15 and you want it to have enough oomph to get someone's attention further than a football field away.

I vote for the 6.8 SPC. A ballistics chart comparison shows the 5.56 maintains 1,000 ft lbs of energy out to 100 yards after which it rapidly runs out of steam. You can carry lots of 5.56 ammo and recoil is light. The 7.62x51 still has 1,000 ft lbs of energy at 500 yards and then drops off. You can't carry as much of this ammo as the 5.56, recoil is noticeably heavier than a 5.56, and it requires a heavier, bigger rifle than a M16/M4/AR15. The 6.8 SPC holds 1,000 ft lbs of energy out to about 300 yards, runs in M16/M4/AR15, the ammo and recoil are only slightly heavier than .223.

Poke around a few hunting websites and you'll find the 6.8 is preferred by many hog hunters for its terminal performance. It also performs very well on deer.

Having spent more than few years in the service of Uncle Sugar at the tip of the spear and having a keen appreciation for weight conservation, my vote goes to the 6.8 as the intermediate cartridge of choice to settle international conflicts at the infantry squad level.
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Old February 17, 2020, 17:12   #6
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One thing I wonder about is to get improved performance out of military ammo then why not use hollow points or balistic tips? Governments kill people in so many more horrible ways the Geneva convention is worthless. We won't use hollow points but depleted uranium is ok
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Old February 17, 2020, 18:32   #7
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I think that the Hague and Geneva Convention treaties are BS for basically the reasons stated above. Also, war is about killing or injuring people. If they're dead, they're effin' dead. Doesn't matter too much how they got that way at the end of the day.

Problem I have with 6.8mm SPC is that it's got a stubby little bullet of poor BC and I doubt that it tumbles or fragments in tissue as reliably (without using HP or SP ammo--again BS, and the US never signed those provisions of those treated, though we still abide by them). A lot of 7.62x39mm ammo did the same until the bullets were redesigned to be more ass-heavy.

That's why I'm looking at like .276 Pedersen or 7.35mm Carcano or even .280 British or 6.25mm British. .280, .276 and 7.35mm fired rounds of decent heft at fairly high velocities for pretty soft recoil compared to .308. The bullets also had very good BCs and were known to be capable of tumbling or fragmenting on impact with soft tissue with ball or even AP ammo. And 6.25mm was a fairly heavy bullet for it's size with a good BC and excellent long range penetration and terminal effects for marginally more recoil than 5.56mm and more energy than 5.56 or 7.62x39 at all ranges.

Of course, 6.25 wasn't optimal by the British Army's admission due to casing design, .280 was ultimately throttled to make near .308 levels of recoil and such to get similar performance, and .276 and 7.35 are as long as or longer than .308 in terms of OAL.

However, .276 Pedersen had a heavily tapered shell casing like 7.62x39 and 8x50mm Lebel. Tapered rounds in theory are easier to extract from a chamber--a theory that with modern designs isn't quite as sound as originally though--but present issues with stuff like acutely curved mags (think AK-47 and Chauchat LMG mags) and such.

If .276 had a less aggressive taper, it could hold more propellant for the same casing length, or the same amount in a shorter casing.

IMO, big problem is that there's a gap between the 56-58mm OAL rounds common in AK and AR platform weapons, and the 71-72mm OAL rounds like .308 and 6.5mm Creedmoor. I certainly want to avoid a round with a .308's OAL if possible. And if you stick to the AR-15/AK-47 sized rounds, you're either going to have to deal with short ranged rounds with poor BC and ballistic performance, or using shorter shell casings.

Also, problem is that also creates a gap where you can get out-ranged by someone with a GPMG or DMR if you have a 5.56mm rifle or one in 7.62x39. But everyone and their brother, sister, aunt, uncle, mother and father have a rifle in armed forces use in one of those calibers.

One can argue that NATO's adoption of 5.56mm and .308 was a mistake, but the Russians are kinda in the same boat with 7.62x54R, 5.45mm and 7.62x39mm.

I'm arguing that if the US Army wants overmatch on intermediate rifles, a new cartridge concept is probably needed (though I don't think that their 6.8mm rounds capable of matching or exceeding .308 ballistics--and probably with similar levels of recoil and lack of control--is the answer).

I'd say that maybe a more compact 6.8-7.62mm round with ballistics like 7.35 Carcano or .276 Pedersen might be an answer. However, everyone has different preferences and experiences.

Maybe a better answer could be the 7x41mm Polish round designed in the 1970s in Poland for a rifle to replace the Polish version of the AK-47. The round was based on an advanced version of the 7.62x39mm, and fired a 7mm about 120 grain bullet at over 2500fps and with well over 1600lbs/ft of energy.
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Old February 18, 2020, 13:05   #8
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OK, I did some research on .280 and .276 Pedersen. Here's maybe the specs I'm looking for:

MV of 2600-2750fps with a 125-130 grain 7-7.62mm (.284-.308) bullet. ME of about 1800ft/lbs. Case with a .445-450 inch rim/base diameter, a taper similar to .308 or .30-06. Basically like a .276 or early .280 but with a shorter shell casing than .276. Anyone want to weigh in on how long such a shell casing would probably be or possibly even chamber pressure (note, I haven't been able to find defined info on .280 British or .276 Pedersen chamber pressures)?

Or would like the 7x41mm I've referenced be even better?
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Old February 18, 2020, 13:53   #9
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I think my choice would be something similar to the Tac 6, a 6mm from a 6.8 case. You can pack 25ish cases into where 30 5.56 cases go, but a 6mm, while only marginally heavier and larger, has proven to take deer effectively since its inception as the .243 Win. The Tac 6 will push a 105gr projo over 2700 fps from 18" of barrel (1700 ft/lbs energy), and to 2800+ from 22" (~1820ft/lbs). 105gr is SIGNIFICANTLY more mass than the 55 or 62gr normally used in the 5.56, and even about half again as heavy as the special 77gr ammo that's in use. It's notoriously accurate, and from a plastic case would probably come in real close to a 1:1 weight ratio when compared to a 5.56 cartridge.

It should check all the boxes you're looking for, and maybe a few you aren't.

Last edited by jhend170; February 18, 2020 at 13:58.
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Old February 18, 2020, 17:35   #10
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I think my choice would be something similar to the Tac 6, a 6mm from a 6.8 case. You can pack 25ish cases into where 30 5.56 cases go, but a 6mm, while only marginally heavier and larger, has proven to take deer effectively since its inception as the .243 Win. The Tac 6 will push a 105gr projo over 2700 fps from 18" of barrel (1700 ft/lbs energy), and to 2800+ from 22" (~1820ft/lbs). 105gr is SIGNIFICANTLY more mass than the 55 or 62gr normally used in the 5.56, and even about half again as heavy as the special 77gr ammo that's in use. It's notoriously accurate, and from a plastic case would probably come in real close to a 1:1 weight ratio when compared to a 5.56 cartridge.

It should check all the boxes you're looking for, and maybe a few you aren't.
Thing is that (though by coincidece) the British kinda did the same with the .280 British shell casing with the 6.25mm bullet that weighed 100-105 or so grains, pushed out at 2650fps and over 1600fps of energy. It could also blast though a standard armored army helmet at nearly 700 yards range.

However, it wasn't fully optimized (definitive casing likely would've had more in common with the .270 British/.270 Enfield round, being longer and slimmer) and was abandoned when the 4.85mm round was developed. Oddly, the .270 British/Enfield round had a base diameter similar to .276 Pedersen and 7.62x39mm and resembled a shortened .276 with a less aggressive taper and a much lighter/lower BC 7mm bullet.

So what you're saying was sort of done before, but the British round didn't make it to serious production, though the Tac 6 has found acceptance in the small cal hunting world.

If you want to go small caliber, it's def. worth a look (since it seems similar to the 6.25mm British which probably would've been a great small cal round), though I do prefer a bit of a larger hole and maybe a bit more mass for what I'm thinking of.
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Old February 19, 2020, 03:55   #11
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My Idea of an ideal Military round would be something like a 7.62 X 45 Checz Necked down to 6.5 It would be a so called 6.5 Grendel Magnum !

My guess would be 120Gr Bullet at 2600Fps


https://en.wikipedia.org/wiki/7.62%C3%9745mm
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Old February 19, 2020, 06:55   #12
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5.56x45 77gr OTM. No need to change anything. Just go with an SPR type main rifle instead of a carbine then add a 1-6x power optic.
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Old February 19, 2020, 15:39   #13
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5.56x45 77gr OTM. No need to change anything. Just go with an SPR type main rifle instead of a carbine then add a 1-6x power optic.
I'd also agree with you there, or maybe use a heavy bullet based on like the Mk 262 or Mk 318 if you want to stay with 5.56mm. Biggest issue is that 5.56mm (or 5.45mm for that matter) really need at least a 16 inch barrel to do much beyond M1/M2 carbine range (the .30 Carbine wasn't known as being very effective beyond 100-150 yards). IMO anything under 16" is too short, even for 7.62x39 or even .308.

Hell, it should be noted that the British found that the optimal caliber for an intermediate round was 6.5-7mm give or take like .25 or .50 of a millimeter or so. And that was back in 1945.

I've also done some further research on .280 British. The most commonly found version of the round is known as the .280/.30, as it adopted the .47-.473 base/rim diameter of the .30-06, 8mm Mauser, and the .30 T65 (future .308 Win/7.62mm NATO). Originally, it had a base diameter of .458, just slightly wider than the approx .45 of 7.62x39, .276 Pedersen, or .270 British. And most early versions of the .280 (before being hot-rodded to make near .308 ballistics) were ballistically copies of the .276.

It should be noted that the British Army tested Vickers built Pedersen PA and PB rifles in the 1930s and had a fairly sizeable stock of .276 PD-42 and similar ammo. I don't know if the .276 influenced British Army thinking with the .280 initially, but I just find it a bit more than coincidence the similarity between .276 Pedersen and .280 initially, even the early .280/.30 variants.
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Old February 19, 2020, 15:45   #14
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I like the AK 7.62x39 round more than 5.56 , ijust don’t personally like the AK platform because of its low adaptability..

7.62x51... no.. it’s good for a DMR though

5.56.. it’s the compromise that keeps on compromising... in my TAP , weapon and pouch I carried a total of 11 mags... it was comforting to have that much ammo at times

The only rifle I currently own is a M4 type gun because of its affordable cost, adequate performance , ammo availability and high adaptability... and if it gets stolen or taken from me I won’t cry too much at the financial loss.... until I can get my hands on another

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Old February 20, 2020, 12:59   #15
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Hell, it should be noted that the British found that the optimal caliber for an intermediate round was 6.5-7mm give or take like .25 or .50 of a millimeter or so. And that was back in 1945.


It should be noted that the British Army tested Vickers built Pedersen PA and PB rifles in the 1930s and had a fairly sizeable stock of .276 PD-42 and similar ammo. I don't know if the .276 influenced British Army thinking with the .280 initially, but I just find it a bit more than coincidence the similarity between .276 Pedersen and .280 initially, even the early .280/.30 variants.
Hell, it should be noted that I have references that state the British Army studied and tested a .276 cal. cartridge back after the Boar War ended in 1902. A Mauser style rifle and the .276 Enfield were recommended to be adopted, but the onset of WWI found it a bad time to switch to a new caliber.
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Old February 20, 2020, 13:59   #16
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I know of the .276 Enfield (though it's far from an intermediate round!) and was basically Britain's answer to the 7mm Mauser and the .30-06 Springfield. But from what I've heard and read (mostly from Ian Hogg) the .276 wasn't a great round as developed, and World War I killed any chance of fixing its problems.

The rifle designed for the round, though, would be rebarreled in .303 British and .30-06 as the P14 and P17 Enfield rifles, and was highly successful in those guises.
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Old February 20, 2020, 15:46   #17
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I'm gonna say .257 Roberts Ackley Improved with 110gr projectile. Why? no particular reason. Just a good all around cartridge.
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Old February 20, 2020, 23:23   #18
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OK, I did some research on .280 and .276 Pedersen. Here's maybe the specs I'm looking for:

MV of 2600-2750fps with a 125-130 grain 7-7.62mm (.284-.308) bullet. ME of about 1800ft/lbs. Case with a .445-450 inch rim/base diameter, a taper similar to .308 or .30-06. Basically like a .276 or early .280 but with a shorter shell casing than .276. Anyone want to weigh in on how long such a shell casing would probably be or possibly even chamber pressure (note, I haven't been able to find defined info on .280 British or .276 Pedersen chamber pressures)?

Or would like the 7x41mm I've referenced be even better?
Well it hasn't been talked about much so I'll disregard ammo availability and say that there are two cartridges that exist that could possibly fit your specs and they are rounds designed for ar-15 sized rifles. The 30 saber cat and the 7mm Valkyrie. Both are wildcats and google will lead you to a forum where the guys that developed them put all the information. Only down side is making the ammo is fairly labor intensive and hand loader only. There's a lot of potential if they ever went mainstream. Well I guess there's potential regardless but you know what I mean.
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Old February 21, 2020, 01:23   #19
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I actually find the AR-15 and AK-47/47 platforms to be part of the problem as well as popularity of 5.56mm and 7.62x39. Max length of those rounds are 57.5mm or there abouts. To go beyond that means going up to 7.62mm NATO/.308 compatible platforms, which I don't see as a big deal.

The FN SCAR design originally revolved around what would become the SCAR 17, which was optimized for .308 and could be down-gunned to 5.56mm and 7.62x39mm. Problem was US SOCOM didn't like the idea of a 5.56mm rifle that weighed a bit more than a normal M4 for a similar barrel length. Of course, US SOCOM ultimately went along with what FN originally envisioned.

It also seems that the H&K HK433 is designed around a similar concept, based on how it seems that it's upper receiver is a bit longer and quite a bit wider than one that was designed around 5.56mm, and it seems that it'll take a lower that uses .308 compatible mags and such.
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Old February 22, 2020, 12:16   #20
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I actually find the AR-15 and AK-47/47 platforms to be part of the problem as well as popularity of 5.56mm and 7.62x39. Max length of those rounds are 57.5mm or there abouts. To go beyond that means going up to 7.62mm NATO/.308 compatible platforms, which I don't see as a big deal.

The FN SCAR design originally revolved around what would become the SCAR 17, which was optimized for .308 and could be down-gunned to 5.56mm and 7.62x39mm. Problem was US SOCOM didn't like the idea of a 5.56mm rifle that weighed a bit more than a normal M4 for a similar barrel length. Of course, US SOCOM ultimately went along with what FN originally envisioned.

It also seems that the H&K HK433 is designed around a similar concept, based on how it seems that it's upper receiver is a bit longer and quite a bit wider than one that was designed around 5.56mm, and it seems that it'll take a lower that uses .308 compatible mags and such.
I still struggle with what are you trying to achieve. While the military picks a full Metal jacket round that fits their idea of engagement on the battlefield, you as a civilian don't have to follow their tactics. Simply changing the bullet in a 556 to a heavy hollow point will help you reach out and still be effective at range. No matter what you assemble you will have to build a balistic chart that includes wind drift and drop. That's a lot of work.
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Old February 22, 2020, 13:16   #21
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I'm trying to see what's ideal on the Armed Forces end.

One thing though that I do find odd is that the US never signed the portions of the Hague Convention or Geneva Convention treaties that prohibit the use of HP/SP bullets in international warfare which I think is more on the Hague Convention issue of the deal.

I believe that the US Army during the M17 MHS pistol competition looked at not just using 9mm, 9mm+P, .40 and even .45 ACP, but also looked at using hollow point and soft point bullet loadings, too.

One problem with using HP/SP ammo in rifles is effectiveness against cover and especially hard body armor plates. especially at range.

I read recently on TFB that the USMC is considering changing up their rifle training programs to more accurately replicate real life infantry tactics. This includes replicating moving targets, being able to take advantage of combat optics (right now 4X mag with the possibility of adopting up to a 8x mag optic) and training troops to use groin or head shots if they believe a combatant is using hard armor.

This also is intended to take advantage of the optics pushing the effective accurate range of the M4, let alone the M16A4 and M27/HK416 out to nearly 600 yards/meters.

But I'm also referring to criticism of the 5.56mm's lack of accuracy or stopping power beyond certain ranges in Afghanistan, and that maybe a larger, heavier, maybe larger caliber or more powerful round would bridge the gap between 5.56mm/7.62x39mm class weapons and 7.62mm NATO and similar class weapons. Just like the LWMMG program is trying to bridge the gap between 7.62mm NATO and .50 BMG.
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Old February 22, 2020, 13:27   #22
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I remember when the 556 came out during the Vietnam war. They built guns rifled to make the bullet tumble. Gave the bullet yaw so when it hit there was more damage. Then as we moved away from the jungle they changed the rifling twist and bullet weight for stability at longer ranges.

Military built ammo to wound because in a battle of attrition it takes more men off the battlefield by wounding than killing does.

The next war won't be unarmoured combatants like the muzzies, it will be Russian or Chinese troops with armour and tactics like we have never fought.

Door to door with a rifle powerful enough to defeat body armour yet it has optics for 600 yards will be a challenge indeed.
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Old February 22, 2020, 17:25   #23
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Went from one to now 26 AR and Mini 14 style light fighters, SBRs, varmint rifles and more in 6.8 spc II. It's durable as never have broken a part even in my high round count rifles, easy on throats as not overbore, light recoil and carries plenty of energy out to 800 yards. Built an 18" AR 15 using a $190 ARP 5R barrel and tuned $59 trigger that has a pile of 350 to 420 yard first round cold bore varmint kills. At 100 yards it has the same energy as a 5.56 and a 45 acp combined at muzzle. That's kind of mind blowing knowing your poodle shooter at 100 yards is putting same energy on a animal as if shot it with a 5.56 and 45 acp at same time from point blank.

6.5 Grendel breaks bolts and eats throats to gain only a few ft/lbs of energy and a few inches of drop at long range. 22 Nosler and 224 Valkerie are real throat smokers. In larger chassis 6.5 Grendel has quickly become the most popular guy in town but I just got my first 6.5 PRC bolt rifle and stuck an 8-24x tactical scope I had for another project on it and put one of my 6.5 Creed AR 10 projects on hold as have a 6.5 PRC barrel inbound. Will take the extra 300 fps to test barrel life and recoil against my 6.5 Creed's before continue building too many more 6.5 Creed's. Like the mild recoil, good barrel life and range of the Creed but if don't give up much in recoil or barrel life with the PRC it may become the next cool kid on the block.
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Old February 22, 2020, 22:13   #24
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I remember when the 556 came out during the Vietnam war. They built guns rifled to make the bullet tumble. Gave the bullet yaw so when it hit there was more damage. Then as we moved away from the jungle they changed the rifling twist and bullet weight for stability at longer ranges.

Military built ammo to wound because in a battle of attrition it takes more men off the battlefield by wounding than killing does.

The next war won't be unarmoured combatants like the muzzies, it will be Russian or Chinese troops with armour and tactics like we have never fought.

Door to door with a rifle powerful enough to defeat body armour yet it has optics for 600 yards will be a challenge indeed.
That's also the issue I'm having with the US Army's hunt for a new 6.8mm round. Like say .277 Fury. Sig claim that it's rated for up to 80K PSI. Compare that to 7.62mm NATO/.308 Win or .30-06 Springfield which are normally rated for like 62-63,000 PSI.

One, I highly doubt that any issued .277 Fury rounds will be anywhere near 80,000 PSI. Not even any known belted magnum rounds come very close to that.

Two, the .277 Fury, especially out of a 16" barrel is claimed to produce .308/.30-06 levels of recoil and muzzle blast. Yes, I know that the Sig MCX Spear is optimized for use with a silencer (and silencers can function as a form of muzzle brake) and has a recoil mitigation system that involves a recoiling barrel (at least per patent images).

But if the US Army wants that level of power, just go back to 7.62mm NATO IMO.

Problem is I don't think you're going to find an AR-15 platform sized round that will defeat hard armor to a certain level and have longer range without going bigger in terms of likely caliber and certainly overall round length.

That's what I find interesting about the FN SCAR 17 and apparently the HK433. Both it seems were designed around .308 or rounds with a max 72mm OAL. And it's easier to go down in size than to go up. And the SCAR 17 for sure isn't a ton heavier than a 5.56mm rifle though it's in 7.62mm NATO.

And that's what I find interesting about rounds like the .280 British, 6.25mm British and even the 6mm SAW (which some say was a copy in its shell casing design of the definitive version of the 6.25mm).

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Old February 23, 2020, 10:10   #25
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May want to try the 270 AR if want to max the .277 projectile from an AR 15. I was able to acquire 250 rounds of 75 grain 6.8 AP and 250 rounds of 97 grain 6.8 AP for testing which were both rated to defeat NIJ 4 armor at 100 yards. From an 18" 5R and 20" 3R barrel the 97 grain was able to not only defeat NIJ 4 at 100 yards but busted a name brand NIJ 4 plate and military soft armor panel at 150 yards with enough retained energy and pent ration for a definite kill shot. The 75 did as advertised at 100 yards and didn't have enough Level 4 plates to keep busting them indescriminately. I did test the 75 and 97 grain to 250 yards on NIJ 3 plates with NIJ 2 soft armor backer which is what our troops are issued and both penetrated their plate on first round.

Considering most people run NIJ 3 or 3+ plates in military issue carriers knowing I can burn an IOTV military issue vest with a single round out to 250 yards more than satisfies my needs. In fact I sacrificed a current issue front plate and soft liner to prove this to myself then took the rear plate and liner, set them at 250 yards and tapped the trigger in binary mode in which both rounds impacted within three inches of each other and it was a horrible mess. Maker of this ammo supplied it for me to test ballistic barriers am installing in churches and corporate settings with agreement would not post photos or name them as do not want to be innovated with people trying to use fake credintials and LEO letters for them to try and verify.

Have about 150 of each left and was able to buy a 500 round box of the 97 grain and have been puthe on notice won't be able to buy more till provide them with evidence a lot of rounds have been fired into test barriers and information shared to help them in their sales pitches to Law Enforcement and military agencies. Recently pulled the 4-12x Leupold off one of my 18" Noveske AR 15s and swapped on a 36x target scope. Only had it at the closest range to house thus far which is only 100 yards. Using Speer 90 grain TNTs the have been sorted into three weight batches (wife will go through up to 5,000 projectiles and separate them into three boxes based on weight then they go throught a pointing die to true the points, are coated with Tubbs boron nitride coating, and are boxed together by how she separates following loading) my first session to date testing accuracy with a true high power target scope am getting ten shot groups from 0.55" to 1.15" with median groups being 0.73".

In this test I would load 15 round magazines with 12 rounds. First round is fired into the berm then next ten into target with final round cycled from chamber. Let rifle cool a bit and repeat which these are the same varmint loads I am using for a pile of 375 to 420 yard first round cold bore varmint kills. Have not tested with match bullets yet as my TNTs after segregating by weight, points trued and coated with a coating that exceeds moly by a factor of ten are cheap and shoot so well I really don't need anything more accurate though for longer ranges.

Will probably switch to my 110 grain HPBT match which get points trued and boron nitride coating to take advantage of the higher ballistic coefficient when go to my 250 yard range and to shoot farther and have a good bench, wind flags and target holders it's a bit of a drive so most of my testing is done to 250 yards after dial things in at 100 just around the corner. Have discovered if a load does well at 250 odds are after my 100 yard, 200 yard and 250 yard testing have good data and loads perform as predicted at longer ranges. 6.8 is both very accurate and can penetrate armor at distance with correct projectile.
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Old February 23, 2020, 14:11   #26
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I'm wondering which is the most optimal for modern use:

.223/5.56mm with heavier bullets though without making the mistake that the US Army made with the M855A1 round with durability in most 5.56mm weapons in current use

Something like a .224 Valkyrie or a larger caliber version

A revival of the .280 British as the British Army designed it, or a .30 version

A revival of the .276 Pedersen or 7.35mm Carcano, or a shortened variation using a 6.5-7.62mm bullet

Or a .308/7.62mm NATO loaded to .280 or .276 Pedersen performance (lighter bullet at high velocity), or like the Japanese Type 64 or Spanish 7.62x51mm CETME round?
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Old February 23, 2020, 15:22   #27
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The military goes with a holistic view of its fighting man aND picks a particular caliber for many reasons then works with that caliber and tactics to bring about a desired performance. A full performance in not just balistics but weight and number of rounds you can carry. It's obvious the 308 didn't fit the way the military wants the battles fought.

Any new cartridge still has to fit the way our men are trained to fight. Given a more accurate round that changes everything else ain't going to happen. Heavier rounds means less firepower on the battlefield.

Lets say they go to an 87 grain 25 cal bullet that fits in the arms they have today. I have seen the 250 savage kill at awesome ranges and it is an 87 grain bullet at 3,000 feet per sec. They could probably put that in a rifle case that feeds but they would use fmj bullets and defeat what it's intended purpose is.

You as a civilian can build anything you want and even bring back the failed Britt rounds if you want to but the military is slow to change because they have a winner now.
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Old February 23, 2020, 20:48   #28
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Buddy of mine was a USMC Armorer for 20 years and attached to USSOCOM during Gulf 1 and 2 before retiring as was tired of being constantly deployed. He still has lots of contacts through his years working with joint Army, Air Force, Navy/Marine Corp armorers when in the Gulf as they worked together on weapons for Delta, 75th Ramgers, SEALs, Force Recon and Air Force specialty teams.

Even after accepting the Mk 13 Mod 7, Marine Corp is resisting any variation from 7.62×51 as proven by following their huge purchase of Mk 13 Mod 7s in 300 Win Mag which were fielded last year they already intend to replace the Mk 13 Mod 7 with the Barrett ASR because it can fire 7.62×51 which wears barrels less and is easier to train snipers on. They can swap barrels to 300 and 338 Norma Mag as needed on the ASR for longer range but the goal he says is to do an end run back to the 7.62×51. They have ear marked four million dollars for ASRs immediately with more to be ordered in 2021.

Meanwhile he says Marines as well as many troops under USSOCOM are already fielding SAWs in 6.8. General "Mad Dog" Maddis has been one of the biggest supporters of the 6.8 and swapping the entire M4 line over to 6.8 along with squad level SAWs. Army has already announced intention to swap from 5.56 to the 6.8 just exactly what exact final cartridge design is up in the air. The goal is to have them going into the field by end of 2020 though design delays will likely push that back.

My buddy says one of the busiest projects his former workers are doing now is converting M14s from 7.62 to 6.5 Creed which all branches say is just a temporary fix till the 6.8 telescoping cartridge reaches final design. Looks now like we will have three different 6.8 cartridges that all use the same steel case head but have three different length brass case bodies to accommodate powder charges to accomplish ranges necessary for a group or mission. All will then share common projectiles with the probable most prolific being the compressed polymer/powdered copper compressed projectile developed by ARX out of Savanah GA and recently purchased by Ruger.

Goal is single bolt face, single bore diameter and shared projectiles for 85% of man carried arms with length of case only difference based on terrain and common ranges for a deployment. Seems to me only making a single diameter projectile, case head and barrel diameter would save a ton of money. The heavy longer bullets developed for the longest cases could also be used in short cases for subsonic use and like the M855A1 and M80A1 would not have to develop the same design for two different bore diameters. While many say the new program is carved in stone others claim it's all still in developmemt, often both opinions coming from same departments based on any particular day they are asked. Guess we will have to see but the sure thing is something is going to change which in the short term will probably dump a lot of surplus 5.56 and 7.62 on the civilian market with luck.
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Old February 23, 2020, 21:04   #29
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Oddly, if the British stuck with the .280 and adopted the 7mm Mauser (both the .280 and 7mm Mauser shared the same bullet design) or opted for the .276 Pedersen and adapted the .280 to it's bullets (which I think were of roughly the same design, but usually lighter than 7mm Mauser), they could've done the same thing.

Of course, they didn't think of that at the time, really.
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Old February 25, 2020, 05:36   #30
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Oddly, if the British stuck with the .280 and adopted the 7mm Mauser (both the .280 and 7mm Mauser shared the same bullet design) or opted for the .276 Pedersen and adapted the .280 to it's bullets (which I think were of roughly the same design, but usually lighter than 7mm Mauser), they could've done the same thing.

Of course, they didn't think of that at the time, really.
With the US doing lots of backdoor dealings to convince other nations to support the .308 as the standard NATO cartridge (US would only adopt a US created cartridge, so it was up to the other members to either accept it or no standardization) in exchange for a standard rifle (which the US reneged later), there was no "British stuck with the .280."
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Old February 25, 2020, 06:09   #31
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This is a follow up to the High End Intermediate Round discussion. Here, I'm looking for opinions on what the best extant intermediate type round out there now, or if a round that never came to the fore should be revived for a second look, or if something new should be pursued as far as caliber, case size or both.

This goes to the reality that modern 5.56mm, 5.45mm or 7.63x39mm rounds are often limited to 300-400 yards or meters due to ballistics and such. This also ties in to something I read on The Firearm Blog about the USMC wanting to revise their training in the next couple of years to more simulate tactical shooting in combat, and to take advantage of modern optics that allow for easy engagement out to 500-600+yards/meters.

That alone in my mind would suggest the desire for a new round, possibly in between 5.56mm/7.62x39mm and .308 Win/7.62mm NATO in performance.

I know that some will argue why not just use 7.62mm NATO, or why didn't NATO use the .280 British round back when it was offered, and so on.

That's part of the point of this discussion, or if something newer or maybe obscure can fit the bill.
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Old February 26, 2020, 16:13   #32
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Sorry to resurrect this topic, mostly because the logical conclusion is that there's no one logical conclusion to suit all comers.

However, I did find this forum post online that's got a pretty good chart that refers to specs of various "intermediate" rounds past and present as far as name, caliber/case length, MV and ME:

http://forums.delphiforums.com/autog...gid=2017136638

Just wondering if anything pops out to you guys.
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Old February 26, 2020, 17:12   #33
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Ideal Intermediate Round (Past, Present, Made Up)

If low recoil and velocity are important to you, I've always been fond of Arnold's railguns:

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Old February 27, 2020, 09:07   #34
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Actually, the strangest thing about that chart I posted is that the 7.75x40mm Geco round is listed as the most powerful of them (muzzle energy wise). That being said, I've never seen that info (most of what I've read on the round is that it fired about 130-140 grain bullets at 2250 fps). Which is interesting given that the Geco round is sometimes sited as being inspiration for the 7.62x39 and its offspring that includes the 5.45x39mm, .220 Russian/.220 Lapua and the 6.5mm Grendel.

And it's also thought that the round has a OAL of only 55-56mm.
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Old March 02, 2020, 01:14   #35
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I was also reading up on M855A1 and Mk318 today. I know that M855A1 got a bad rap because the US Army initially loaded it to 7.62mm NATO/.308 Win./.30-06 chamber pressures. However, it seemed that early problems with M4s and every rifle tested in the Individual Carbine trials having issues lead to changes.

From what I've heard, for small caliber rounds, the M855A1 and Mk318 does have excellent terminal effects, and the AP version of the M855A1 (I think it's called the M995) can defeat level IV hard armor on the first hit (so can 7.62mm NATO M993, which is the AP version of the M80A1).

Between those two rounds, I don't see the need for the US Army to reinvent the wheel caliber-wise for the near future. Especially with the investment made to get the M855A1 and M80A1 into the field.
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Old March 02, 2020, 09:22   #36
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Old March 02, 2020, 11:22   #37
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5.56x45 77gr OTM. No need to change anything. Just go with an SPR type main rifle instead of a carbine then add a 1-6x power optic.
Quote:
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I'd also agree with you there, or maybe use a heavy bullet based on like the Mk 262 or Mk 318 if you want to stay with 5.56mm. Biggest issue is that 5.56mm (or 5.45mm for that matter) really need at least a 16 inch barrel to do much beyond M1/M2 carbine range
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Old March 02, 2020, 11:26   #38
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6.5 Grendel = AR magazine and troop-level distribution

6.5 Creedmoor = AR-10 magazines and 1000 yard performance with low recoil

.416 CheyTac = Drone-mounted rifles and Very Specialized cases
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"How we burned in the prison camps later thinking: what would things have been like if every security operative, when he went out at night to make an arrest, had been uncertain whether he would return alive and had to say good-bye to his family? Or if during periods of mass arrests people had simply not sat there in their lairs, paling with terror at every step on the staircase, but had understood they had nothing to lose and had boldly set up in the downstairs hall an ambush of half a dozen people with axes, ham- mers, pokers, or whatever else was at hand. . . . The Organs [police] would very quickly have suffered a shortage of officers . . . and notwithstanding all of Stalin‘s thirst, the cursed machine would have ground to a halt." - A. Solzhenitsyn, Gulag Archipelago
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Old March 02, 2020, 16:30   #39
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6.5 Grendel = AR magazine and troop-level distribution

6.5 Creedmoor = AR-10 magazines and 1000 yard performance with low recoil

.416 CheyTac = Drone-mounted rifles and Very Specialized cases
All of them doable in modern weapons with tolerable weights:

6.5C vs .308:



6.5 Grendel vs 5.56:



Cheytac 375 and CT 408 compared to 50 BMG:

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Old March 04, 2020, 20:52   #40
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From what I've heard, for small caliber rounds, the M855A1 and Mk318 does have excellent terminal effects, and the AP version of the M855A1 (I think it's called the M995) can defeat level IV hard armor on the first hit (so can 7.62mm NATO M993, which is the AP version of the M80A1).
m995 & m993 (ap3 & ap8 as they are known outside our shores) aren't the AP version of the new A1 stuff. M995 & m993 existed looong before A1 versions.

Also, m995 won't defeat lvl IV plates. Google buffman range on youtube, he does lots of cool stuff. Even ap4 (newer upgraded version of ap3, 62gr bullet vs 53) struggles on lvl IV. 5.56 simply does not have enough oomph to defeat lvl IV with any regularity at distance no matter how good of core construction it has.

Just an fyi, not trying to come off as rude.

https://youtu.be/wcvwOFjacvA

M993 on the other hand.. thats some awesome stuff. I couldn't catch one in my AR500 plate until almost 300m out of my 26" sendaro. Anything closer & it just looked like you put a hole in it with a plasma cutter. I shot the same plate with 30-06 M2AP, Russian ShKas 7.62x54R B32 & neither came close to penetrating at any range.

Have a great day everyone.

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Old March 04, 2020, 23:41   #41
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Problem is that I don't see 5.56mm going anywhere very soon. Problem with the .277 Fury that Sig is pushing is that I don't see what it can do that .308/7.62mm M80A1 or M993 can. And Sig's claims that it's rated for up to 80,000 PSI? 7.62x51mm NATO/.308 Winchester and .30-06 Springfield/7.62x63mm are rated for like 62,000 PSI. No known rifle ammo comes close to 80K PSI, not even belted magnum rounds.

I know that there's talk of standard M80 having inconsistent accuracy beyond 800 yards/meters range, but why not use heavier bullets or the A1 rounds or AP ammo as standard.

I have to agree with some TFB articles that I've read in that 7.62x54R is virtually identical to .308 ballistically as well as most military loads of .30-06. I'm not sure where the US Army experts are getting that PKMs or SVDs are out-ranging guys with 7.62mm NATO weapons when real life info suggests that the NATO weapons should be equally matched if not somewhat superior. That's not to take anything away from the designers of the PKM or SVD, but I think it's a bit farfetched for US Army Generals to make such claims.

Also, I'm not sure about the ME and accuracy that M855A1 makes compared to the SS109/M855, aside from the fact that the A1 round is far superior in performance out of M4 carbines and SCAR 16s vs the earlier rounds. And it's claimed to have better terminal effects than most 7.62x39mm ball ammo.
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Old March 05, 2020, 01:34   #42
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Best intermediate ?

50 BMG.


Larger than 5.56

Smaller than 20mm.

In other words, perfect.



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Old March 05, 2020, 07:28   #43
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Way I see it with intermediate rifle calibers, it's either you can try and mimic or exceed the killing/stopping power of rounds like the .30-30 Winchester or .30 Remington, which may or may not be practical.

Or, you can match or exceed the stopping/killing power of magnum caliber pistol rounds when shot out of a carbine length rifle or a short rifle.

For instance, even 5.56mm M193 hits harder than a .44 Magnum, a round that when used out of revolvers or the Desert Eagle automatic pistol is used to drop large game, let alone lever action or even some semi-auto rifles (Ruger even used to make a semi-auto hunting rifle partly based on the M1 Carbine chambered in .44 Mag).

Granted, those are two rounds used in two different roles usually, but if a .44 Mag or .454 can put down large game, so can a .22 rifle or .30 class intermediate round if the round produces similar or better energy transfer, especially at longer ranges. Which is also useful in an armed forces context if said rounds can deal with an intended level of threat. Which what is the level of threat being looked at is the issue.
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Old March 25, 2020, 03:55   #44
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A 140gr 7mm x 45.
Shorter and lighter than 7.62 nato, but much better ballistics than 7.62 x 39 type.
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Old March 25, 2020, 05:04   #45
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Had another 1,000 22 Nosler cases plus some 224 projectiles needed for project I intended as my 22 Nosler and 458 SOCOM inventories are lowest of all poodle shooter cartridges. Already have a load worked up for M855 green tip and M855a1 "bronze" tip improved 5.56 projectiles in 22 Nosler so ordered 300 62 grain Barnes 62 Grain Tac-X Boat Tail copper solids. Used some once fired to adjust load to get approximate velocity am pushing the M855 and M855a1 so the Barnes bullets would roughly dope the same at distance.

Built a pair of twins which are loosely interpreted Mk 12 Mod H clones using 18" 5R melonite treated barrels in 22 Nosler for a light fighter with ability to use all the 5.56 specialty projectiles at an extra 300 to 350 fps with minimal effort. Had to buy a premium 5R stainless barrel and have melonite treatment done myself to hopefully increase throat and bore life. Have refined my three 62 grain fighting loads to approximate velocity of 3,325 fps with each of the 62 grain projectiles. Pushing M855, M855a1 and now the Barnes Tac-X copper solids at this speed are a solid performer at longer ranges and deal with Level 3 rifle plates well while getting expansion and performance on non armored or soft armor targets.

Having my load data for M855/M855a1 ran a quick ladder test to match velocity with the Barnes Tac-X then did a small batch to test accuracy which was sub MOA at 100 yards thus good enough for a fast track load. Stuffed 250 of the Barnes Tac-X another 250 of my valuable as gold M855a1 projectiles and 500 M855 projectiles in cases for another 1,000 rounds on 22 Nosler for my fighting rifle pair. Have a pair of varmint builds using 20" 3R melonite and final pair using 22" button rifled match stainless am careful to keep round counts low and use mostly 70 grain projectiles.

Was actually amazed at how many M855 and M855a1 have piled up in 22 Nosler as slowly built inventory. Have just over 1,000 M855a1s allowing a bandoleer of loaded mags, 1,000 in storage and enough in range locker to keep scopes verified. Have way more M855 along with Hornady 62 grain boat tail FMJ. Adding the Barnes copper solids have 25 extra to test while keeping my 250 count boxed up for use. Initial tests during load development lends this to be a very lethal round for a tiny bore poodle shooter.

Am likely pushing enough inventory to totally smoke the throats and barrels on each rifle as hoping for 3,000 rounds each before see accuracy fall off but had spare barrels melonite treated to drop in when smoke them at beginning of project. Ordered another 250 of the Barnes Tac-X tonight along with cases and when stuff them will repeat till have enough they can be used for more than a few minutes of sending rounds down range. It's hard building inventory in newish cartridges and newer loads for them when a person is a odd cartridge and wildcat addict.

Really like my Mk 12 Mod H 5.56 "magnums" for light fighters as the extra velocity changes the rules past 500 yards. Plan is if burn all four tunes from initial purchase since use same bolt as 5.56 just swap them over to 5.56 if desire or 22 Nosler becomes difficult to support by doing a simple barrel swap. Both have Vortex Viper 4-16x 50mm glass and make stunning fighting and varmint rifles. With both set up to fire four different flavors of 62 grain ammo came up with an average drop table that is close enough for all won't miss man size creatures unless totally miss range and wind estimation. Another intermediate round in very light rifle that will be very hard to find ammo that didn't bring with you.
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Old March 25, 2020, 23:19   #46
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6.5 Grendel
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Old March 26, 2020, 05:03   #47
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6.5 Grendel
Try 6.5 with high rate of fire light fighting rifles and see how bore life holds up and count number of bolt failures. Put a binary trigger in 6.5 Grendel and start running 400 to 600 rpm rate of fire mag dumps and the rifle will have bolt failures due to large rim diameter causing thin weak shoulders on bolts. If used a oversize non milspec upper such as the 300 OSSM and better WSM builds then bolt issues could be solved but you have moved away from a milspec M4/AR 15 upper. Also it will smoke a throat too quickly. Reason my 22 Nosler Mk 12 clones use Hiperfire 24E single stage, semi auto triggers as a few high rpm mag dumps would smoke the throats though have yet to break a 22 Nosler or 6.8 spc II bolt in over ten thousand rounds now.

If look at ballistic charts comparing 6.8 spc II and not spc 1 data next to 6.5 Grendel drop out to 800 yards is just a few inches difference. Have built ARs, always a minimum of two in 20 Practical, 204 Ruger, 223/5.56, 5.7×28, 22 Nosler, 6×45, TAC 6, 243 WSM, 6.5 Grendel, 25/45 Sharps, 25-6.8, 6.5-6.8, 6.8 spc I & II, 270 AR, 277 Wolverine, 300 Whisper/BO, 300 OSSM, 458 SOCOM along with some others hard to remember off top of my head. If not so deep into 22 Nosler already might have gone 224 Valkerie route but too similar to add a ballistic duplicate round to test and support.

Have 18" 5R, 20" 5R and 3R along with pair of 22" 6.8s have shot side by side with 6.5 and will do it again but promise by end of a all round accuracy, range and durability test the 6.5 will not out perform 6.8 by enough to warrant a burned out throat and broken bolt or two in durability phase. Out of curiosity built a 6.5 using a low/mid grade melonite barrel, properly tuned gas and buffer system, was accurate enough for barrel but soon as we snapped it on a M16 select fire lower we broke two Carpenter 158 equivalent shot peened bolts in short order. After second bolt failed dropped in a JP Enhanced High Pressure bolt to complete the two day testing of 6.5 vs 6.8 and it held together till end but throat was burned out and accuracy dropped off by over 60%.

We took 5,000 rounds of 6.5 and 5,000 rounds of 6.8 in a pair of uppers built with same components except barrels and bolts. After 2,000 rounds of bench shooting with high power optics, mid power optics, running drills, structure clearing drills, ringing steel then we spent next 2,500 rounds trying to break each with M16 select fire lower and the 6.8 ran all rounds without failure. It took three bolts to complete the 2,500 round torture with 6.5 and first two were as close to same material and maufactuing technique used on 6.8 bolt. The $140 JP bolt held up for more than both the mid priced 6.5 bolts combined. We used a $79 bolt on the 6.8 and $89 bolts on 6.5 initialy. Would have to pull all the folders and receipts to quote each coponent. After torture test used last 500 rounds to repeat accuracy tests with mid power and high power glass.

The 6.5 was done, 2,500 rounds of full auto had ended it's ability to make hits past 200 yards while the 6.8 shot pretty much same as did starting the test. It lost some accuracy past 500 yards but not enough to matter if shooting in a combat situation. For ground hogs and coyote it would have been a bit more challenge but the 6.5 was pitching knuckle balls past 500 yards. If build a 6.5 and use for hunting rifle with ten to fifteen round magazine and shoot it at moderate rate of fire about as quickly as can take the follow up shot and transition to next varmint then let it rest. Take to range and shoot ten round groups with cooling session between it does shoot just a few inches flatter at long range and bucks wind fair amount better than 6.8 but if have to use it for a high duty cycle fighting cartridge in a milspec AR 15 /M16/M4 it eats itself in less number of rounds that may be fired rapidly in a single deployment.

The 6.8 holds up as well as 5.56 and maybe better, not run up as high of a round count on a single 6.8 as some of my 5.56 rifles yet but am reeling in on the five figure round count on couple now and that 10,000 to 15,000 round duty cycle usually tells the tale. It would break me buying parts to keep a 6.5 going 15,000 rounds as assume would be two barrels and four bolts minimum if just abused it occasionally on binary fire. My 22 Nosler have an even worse issue with throat and barrel wear. Industry says 2,000 rounds accurate and another 2,000 as plate ringer then dispose of barrel. Been told by vendors on my true match grade 22 Nosler more like 1,000 rounds of accuracy and 2,000 plate banging then replace. Have bolt rifles with 800 to 1,000 round max barrel life and can deal with such if know it but if bolts and other parts fail before barrel then it's not for me.

I liked my 6.5s at first, killed a lot of coyotes with them. When broke first bolt on low run count rifle delved deeper into durability testing. Had 6.5s before I had 6.8s as read the charts and hype. Bottom line is if I know my drop table two to eight more inches drop at range matters none. 6.5 has tad more retained energy dowrange tested with factory ammo but 6.8 can be loaded much hotter than factory or charts without sacrificing durability. They still load to spc I pressures in most cases which is not what us 6.8 shooters are doing at our benches. Not a 6.5 hater, just found cartridges that do basically the same job and are much more durable in similar rifles.
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Old March 26, 2020, 06:41   #48
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.308 is the ideal intermediate round. If it has too much foo in standard form for intended purpose, use 125 grain bullets, H4895, and load accordingly.
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Old March 26, 2020, 11:47   #49
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.308 is the ideal intermediate round. If it has too much foo in standard form for intended purpose, use 125 grain bullets, H4895, and load accordingly.
Ten plus pound rifles loaded are not intermediate in my opinion but to each his own. Currently have a load of ARX frangible polymer 90 grain ×39, 88 grain 308, 35 grain 5.56 and 200 grain 458 SOCOM projectiles in bound. All are same physical size as conventional projectiles of double their weight so if get decent performance out of them could be good to stockpile some bug out ammo using them. Dropping projectile weight in half increases number of rounds a person can carry based on physical strength. Plus I like to play with new stuff.
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Old March 27, 2020, 12:54   #50
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I've long been a proponent of the 6-6.8mm range of cartridges for the military AR size platform.
With current technology, the best lethality in the standard AR platform comes from bullets of 90-130grains at over 2300fps. Bigger bullets are always better if the speed can be kept up and down-range performance stays the same.

I was an early proponent of the 6.5 Grendel. Granted I have not run the tests that Hueyville did. But I had excellent performance from my three rifles with Hornady, Wolf Gold, and even the Wolf steel-case ammo. I have not kept accurate records on round counts, but I'd guess that my 20" standard barrel has at least 1500 rounds and does not show signs of throat wear.

Still, I don't have anything against the 6.8 Remington, either. It far superior to the 5.56mm at all ranges, and is especially useful in the itsy-bitsy short barrels that are so popular these days.

It's all a trade-off. More velocity vs more bullet weight vs downrange energy retention vs close-range lethality vs user experience. It's difficult to draw the line on these. But, I think that it's obvious to almost everyone that the 5.56mm is not an optimum choice for the combat soldier (or Marine )
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