PDA

View Full Version : Should an SP-1 only shoot .223?


scottyb
November 23, 2017, 20:14
My Dad has a Colt SP-1, we looked up the serial # and it was made in 1974.

The receiver is marked .223 so no 5.56.

Sound right?

meltblown
November 23, 2017, 20:25
Yes it is very good to shoot with Pew pew.

Tell your dad to call

croftonaviation
November 23, 2017, 20:45
How is the barrel marked? The receiver marking is inconsequential. I would think 556 would be just fine.

Tom

V guy
November 23, 2017, 21:12
Have we deteriorated this far?

Yes, shoot 5.56.
55 grain is best, just not steel case.

lockjaw
November 23, 2017, 21:38
Have we deteriorated this far?

Yes, shoot 5.56.
55 grain is best, just not steel case.

Some people simply don't know. It is a reasonable question.

As already noted, 5.56 is good to go. Use lighter alright load (55 grain) for b st accuracy.

My 1/12 Colt barrels LOVE this round.... accurate, ugly (smokes coyotes) and relatively inexpensive. https://www.midwayusa.com/product/953830473/federal-american-eagle-ar-ammunition-223-remington-50-grain-tipped-varmint

scottyb
November 23, 2017, 21:50
Thx folks.

Dean762
November 25, 2017, 01:40
The 1/12 twist barrel on the SP1 is optimized for the 55 gr FMJ M193 rd. Of course you can shoot other 556 rds.

This is my personal preference. Absolutely outstanding performance and function, and reasonably priced.

http://www.sgammo.com/product/223-556mm-ammo/1000-rounds-556mm-55-grain-fmj-m193-imi-ammo-made-israel-military-industries

hueyville
November 25, 2017, 10:06
Have seen more than one person shooting green tip or 77 grain ammo at range and wondering why theirs dad's Colt is patterning instead of groupimg. It's fun to hand them some of my 50 grain varmint rounds and see the suprised look when group size closes by factor of 3x to 4x. Trying to explain twist rate to many is like talking fast burst microwave data links with my mother. But just tell them the older rifles were built to shoot 55 grain or lighter bullets and leave the physics lesson out of the explanation.

I bought a used kitchen table build for $200 a while back because owner used a 20" Colt SP1 barrel given to him by a friend. Said he had worked on it for months and just wanted to trade it in on a factory M&P 15. LGS owner does not take home built AR's in on trade for liability reasons so let's employees and hang arounds buy them if so inclined. It had $600 in nice parts not counting the barrel. Paired it with a SP1 upper got in another similar deal with proper A1 triangle handguards which netted me an upper that paid for both the parts rifles free and clear.

Pulled a pair of Palmetto clearance barrels and a flat top upper to put the parts guns back complete and had less than $100 each in two nice shooters once all the parts swapping was done and Colt upper sold. In both cases recommended proper parts swap to owners but both had hit the wall of frustration and rather take a fat loss than invest any more money in their home builds. Have lots of inexpensive parts from other similar circumstances. It's nice to see someone ask a question rather than possibly ruin an original Colt by doing a barrel swap due to inaccuracy.

lockjaw
November 25, 2017, 10:41
The 1/12 twist barrel on the SP1 is optimized for the 55 gr FMJ M193 rd. Of course you can shoot other 556 rds.

This is my personal preference. Absolutely outstanding performance and function, and reasonably priced.

http://www.sgammo.com/product/223-556mm-ammo/1000-rounds-556mm-55-grain-fmj-m193-imi-ammo-made-israel-military-industries

Yep, the IMI ammo is good to go across the board.

I have found that 62+ grain ammo can be hit and miss through assorted Colt 1/12 barrels. Some shoot great, others don't like heavier bullets. They didn't keyhole like some of the Internet BS folklore will tell you, but some groups did open up quite a bit (some barrels more so than others).

ftierson
November 25, 2017, 10:49
It's nice to see someone ask a question rather than possibly ruin an original Colt by doing a barrel swap due to inaccuracy.

Of course, the original question referred to the difference between .223 Rem. and 5.56x45mm and had nothing to do about accuracy.

As far as I know, Colt chambered for 5.56x45mm from the get-go. Certainly, the SP-1 that I have is so chambered...

Forrest

hueyville
November 26, 2017, 11:20
Yep, the IMI ammo is good to go across the board.

I have found that 62+ grain ammo can be hit and miss through assorted Colt 1/12 barrels. Some shoot great, others don't like heavier bullets. They didn't keyhole like some of the Internet BS folklore will tell you, but some groups did open up quite a bit (some barrels more so than others).

I like IMI ammunition and is my most purchased bulk ammo. In 1999 purchased three pallets for the predicted Y2K end of supply chain. Currently have great price on a pallet of IMI M855 green tip that wife and I are negotiating possibility of purchase. While she knows if I live long enough will easily burn through pallet of 5.56, she is hesitant at present about a single five figure ammo purchase right now even though its under 20 cents a round if go the pallet route. Would most likely hoard it all away as feel once majority of green tip gets surplused it's going to get rare as no incentive to manufacture since military is swapping to M855A1. Once dot gov warehouses get stocked with M855A1 which don't see it being surplused except as pull downs green tip might be a good investment.

As to occasional 1:12 SP1 barrels keyholing with 62 grain ammo being folklore, have a CAR-15 that will prove the theory. It's a very early Colt SP1 1:12 upper on an aftermarket clone A1 lower that starts keyholing any green tip from ten yards and out. Funny thing is at 25 yards it groups under 4" and is deadly accurate with its tumbling bullets. It sits next to the headboard of my bed loaded with green tip for zombie use in the house.

Picture below point of aim was center of the four small orange squares at 25 yard distance. Ammo was IMI NATO stamped green tip. Any 62 grain bullet shoots pretty much same group size and tumbling pattern. Keep meaning to test with ballistic gellitan but not done yet as still learning to use my relatively new high speed/slow motion playback video cameras and want to see test in slow motion video to get real idea of how bullets react in ballistic gellitan but need a day range is totally clear as well because fear what they might do as swap directions in media.

http://i59.tinypic.com/9u0z1e.jpg

No shots longer than 50 feet line of sight in house so if zombies get inside, idea of spitting twirling green tips knowing all will hit center of mass is interesting option. Rack next to bed holds six rifles thus have plenty of accurate options. Can grab suppressed FAL loaded with 220 grain frangible subsonics, scatter gun of death, 5.56 night vision with match barrel, red dot suppressed SBR, suppressed 6.8 or twirling keyholing spewer of tumbleweeds. Also have assortment of handguns with pair of rifles on wife's side but if clearing the house with no intent of going outside may just grab the little nasty thing.

50 grain or lighter bullets and holds 2 MOA at 100 yards. Some 55's shoot fine, others go loopy by 100 yards. No telling how many rounds have been down the bore as came off a Class 3 rifle when owner realized barrel was shot out. Built it to test and have meant to replace but have not done yet though have dozens of barrels laying around. Sometimes it's fun to demonstrate what an old slow twist rifle barrel does in real life so might stay on rifle rest of my life.

SAFN49
November 26, 2017, 12:38
It should be a 5.56 chamber. The best way to find out is get a .223 Armalite (Wylde) throat reamer and check it. It is fine to shoot .223 in a 5.56 chamber but not vise versa.

Now before all the keyboard commandos come out and say 223 and 5.56 are the same thing the throats are different when the barrels are chambered.

Here are pressures from shooting 5.56 in a 223 chamber

NATO in a 5.56 chamber M193 is around 50,000 psi, M855 is 53,000 psi and M855A1 is 63,000 psi which is over CIP.

Take the old M193 and put it in a 223 chamber and test in the same test barrel with the same pressure test you get about 67,000 psi which is not too bad. Only ~4000 psi over CIP.
You take some M855 and put it in the same test barrel and the same pressure test equipment and you get 72,000 psi. Proof load territory.
I don't know anyone that has tried M855A1 in a 223 chamber barrel yet. I would guess 84,000 psi

Moral of the story don't use 5.56x45 NATO rounds in a rifle with .223 chamber.

lockjaw
November 26, 2017, 12:57
Funny thing is at 25 yards it groups under 4" and is deadly accurate with its tumbling bullets. It sits next to the headboard of my bed loaded with green tip for zombie use in the house.



You tout having an infinite amount of experience and knowledge regarding AR platforms and other weapon systems..... I don't have words.

lockjaw
November 26, 2017, 13:11
It should be a 5.56 chamber. The best way to find out is get a .223 Armalite (Wilde) throat reamer and check it. It is fine to shoot .223 in a 5.56 chamber but not vise versa.

Now before all the keyboard commandos come out and say 223 and 5.56 are the same thing the throats are different when they are chambered.

Here are pressures from shooting 5.56 in a 223 chamber

M193 is around 50,000 psi, M855 is 53,000 psi and M855A1 is 63,000 psi which is over CIP.

Take the old M193 and put it in a 223 chamber and test in the same test barrel with the same pressure test you get about 67,000 psi which is not too bad. Only ~4000 psi over CIP.
You take some M855 and put it in the same test barrel and the same pressure test equipment and you get 72,000 psi. Proof load territory.
I don't know anyone that has tried M855A1 in a 223 chamber barrel yet. I would guess 84,000 psi

Moral of the story don't use 5.56x45 NATO rounds in a rifle with .223 chamber.

Sigh. There are a wide variety of chambers dimensions among assorted manufacturers (and the vintages in which they were manufactured) for their 5.56 and .223 applications, especially in regard to AR platforms.

I have yet to hear or read of anymone who blew up or damaged their rifle from shooting mil-spec 5.56 ammo of any grain through their .223 AR, EVER. Heck, I couldn't even find any "internet commando" experience of such. Go figure?

ftierson
November 26, 2017, 13:23
It should be a 5.56 chamber. The best way to find out is get a .223 Armalite (Wylde) throat reamer and check it. It is fine to shoot .223 in a 5.56 chamber but not vise versa.

Now before all the keyboard commandos come out and say 223 and 5.56 are the same thing the throats are different when the barrels are chambered.

Here are pressures from shooting 5.56 in a 223 chamber

NATO in a 5.56 chamber M193 is around 50,000 psi, M855 is 53,000 psi and M855A1 is 63,000 psi which is over CIP.

Take the old M193 and put it in a 223 chamber and test in the same test barrel with the same pressure test you get about 67,000 psi which is not too bad. Only ~4000 psi over CIP.
You take some M855 and put it in the same test barrel and the same pressure test equipment and you get 72,000 psi. Proof load territory.
I don't know anyone that has tried M855A1 in a 223 chamber barrel yet. I would guess 84,000 psi

Moral of the story don't use 5.56x45 NATO rounds in a rifle with .223 chamber.

Yes, the 5.56x45mm chamber (throat) is slightly different than the .223 Rem. chamber.

But, regardless of what it says on the Colt SP-1 receiver, it was chambered for 5.56x45mm M193. The OP's original question was a valid one for someone not knowing this...

M193 is not a NATO round (although many NATO and non-NATO countries also used it). The 5.56x45mm NATO was developed around the Belgian SS-109 bullet (what the US produces as the M855) and was not approved as a NATO spec round until the change to the SS-109 62gr bullet with the steel penetrator. And, of course, to stabilize the 62gr M855 (and, even more importantly, the M856), the NATO spec 5.56x45mm ammo required a change to a faster (than 1/12) twist. Most NATO countries adopted the US spec of 1/7.3 (one turn in 185mm) for the SS-109 ammo, although some also used 1/9 for a bit.

And, essentially, the original 5.56x45mm chamber and the 5.56x45mm NATO chamber are identical.

Forrest

ftierson
November 26, 2017, 13:27
But, regardless of what it says on the Colt SP-1 receiver, it was chambered for 5.56x45mm M193.

If an original Colt rifle, of course. If it has an aftermarket barrel, well...

Forrest

SAFN49
November 26, 2017, 14:32
Sigh. There are a wide variety of chambers dimensions among assorted manufacturers (and the vintages in which they were manufactured) for their 5.56 and .223 applications, especially in regard to AR platforms.

I have yet to hear or read of anymone who blew up or damaged their rifle from shooting mil-spec 5.56 ammo of any grain through their .223 AR, EVER. Heck, I couldn't even find any "internet commando" experience of such. Go figure?

Yeah I know. There was one test report of 5.56 in a 223 SAAMI test bbl @ 77,000 psi.

The only thing I have heard happening was primers popping and jamming AR's.

I just don't think it's a good idea to run 5.56 in a 223 chamber unless you know what chamber you have, it could be very hard on the rifle.

ftierson
November 26, 2017, 14:44
Yeah I know. There was one test report of 5.56 in a 223 SAAMI test bbl @ 77,000 psi.

The only thing I have heard happening was primers popping and jamming AR's.

I just don't think it's a good idea to run 5.56 in a 223 chamber unless you know what chamber you have, it could be very hard on the rifle.

And, while I don't worry too much about all this, I don't disagree with this...

Forrest

V guy
November 26, 2017, 17:46
Original SP1's, and all Colt AR's up thru the late model AR-15 A2 Sporter II, were all marked .223 on the receiver, because Colt was trying to avoid criticism, for releasing a semi-auto version of the M-16 to the crazy public.

My early SP1, and CAR-15 have a bbl's marked C MP B, just like the M-16.

I am not sure if I have ever seen .223 for sale, quite frankly.

Invictus77
November 26, 2017, 18:04
Have we deteriorated this far?


Sad, is it not? :facepalm:

SAFN49
November 26, 2017, 19:06
Original SP1's, and all Colt AR's up thru the late model AR-15 A2 Sporter II, were all marked .223 on the receiver, because Colt was trying to avoid criticism, for releasing a semi-auto version of the M-16 to the crazy public.

My early SP1, and CAR-15 have a bbl's marked C MP B, just like the M-16.

I am not sure if I have ever seen .223 for sale, quite frankly.

I called Remington 8 or 9 years ago and asked what the chamber was on a VTR I just purchased and they said use 223 just like it is marked on the receiver.
So they could not tell me if it was a 223, Wylde, or 5.56 chamber. The bbl is unmarked.

ftierson
November 26, 2017, 19:16
I called Remington 8 or 9 years ago and asked what the chamber was on a VTR I just purchased and they said use 223 just like it is marked on the receiver.
So they could not tell me if it was a 223, Wylde, or 5.56 chamber. The bbl is unmarked.

Yet another reason why Remington is standing on the banana peel...

If concerned, I'd just 'chase' the chamber with a Wylde reamer...

Forrest

lockjaw
November 26, 2017, 20:24
Sad, is it not? :facepalm:

The original OP's question is a viable one, if they are inexperienced. If you do a Google search on the subject, this is one that may land a newbie waist deep in internet folklore and armchair commando BS.

In fact, this thread is probably one of the most on point and constructive, without going off the rails (other than a dude who prepares for CQB combat against zombies by utilizing a shot out 1/12 barrel that keyholes M855 rounds... that was amusing).

:whiskey:

Invictus77
November 26, 2017, 20:35
The original OP's question is a viable one, if they are inexperienced.

My comment was not directed at the OP, who I will add is a "good dude".

:cheers:

12v71
November 26, 2017, 22:42
Pssst... 2 weeks ago I ran 60 rounds of M855 through my old 1967 SP1 as an experiment. Oddly enough it had acceptable accuracy on a 10" plate at 100 yards. Dunno if it was keyholing or not. :whistling: BTW, 855 only makes small pinpoint peck marks on AR 500 plate.

yovinny
November 27, 2017, 09:11
Right from the starting gate, Colt marked mil stuff 5.56 and civilian sales stuff .223
It's political correctness, but really all the same,,,just marked different.

That be why if your sp1 sports a 5.56 marked mag and not one marked .223, its not the original one that came with it or one purchased through a commercial dealer, but rather one liberated from military use.

pistolero1911
November 27, 2017, 17:36
Rack next to bed holds six rifles thus have plenty of accurate options. Can grab suppressed FAL loaded with 220 grain frangible subsonics, scatter gun of death, 5.56 night vision with match barrel, red dot suppressed SBR, suppressed 6.8 or twirling keyholing spewer of tumbleweeds. Also have assortment of handguns with pair of rifles on wife's side but if clearing the house with no intent of going outside may just grab the little nasty thing.



While you may indeed pepper any zombie intruder, you will probably lose valuable time in deciding if said zombie should be peppered with: A) 7.62mm of manliness, aka FAL; B) Shottie; C) Poodle-shooter 5.56 with match barrel; D) Short Barrel Poodle-Shooter - Miniature/Toy Poodle? E) Grendel 6.8 Poodle-shooter; or F) 62 grain Tumbling Dice Poodle-shooter.

Make it easy on yourself and standardize your zombie calibre choice as well as firearm choice. If said zombie is armed, he may get the draw on you as you contemplate the cost / benefit of differing ballistics from a shottie's 00-buckshot v. 62 grain keyhole. K.I.S.S. is key to home defense.

BTW I prefer an M1 Carbine with 110 grain soft-point rounds for tenderizing zombie meat indoors. To each his own.

Just Sayin'

scottyb
November 27, 2017, 18:22
I appreciate all the input and info. My main concern is that my dad not do any damage to his rifle if he should want/need to shoot it. I figured it was ok but it never hurts to ask. I knew it had a much slower twist rate.

Thanks to everyone.