chrome barrel debate (accuracy harmonic resonator sleeve)

[paqmaster]

Could some of you gentlemen please weight the difference(pro & con's) between the two for me, I want to buy a couple & does a 100.00+ a barrel justify the crome!!!
thanks
paqmaster

[ July 31, 2001: Message edited by: gary.jeter ]

[Mfg Eng]

Chrome lined improves corrosion resistance, wear resistance.
Unlined has better accuracy, lower cost.
Chrome should NOT cost $100 unless they are doing one barrel at a time.
The reason chrome affects accuracy is the tolerance of chrome thickness (the thicker the chrome the more variation in thickness)combined with a tendancy to build up inconsistently on sharp edges ("tree") and inability to fill in corners (lack of "throwing power") in the rifling.

[paqmaster]

The 100.00 dollars comes from SARCO, their selling new cromed lined barrels for 145.00 & TAPCO's selling like new w/gas block for 50.00 I was wondering if crome made that much difference to justify 100.00 dollars.
thanks !!

[Kerry]

Another point to keep in mind is that many people may wish to shorten a FAL barrel or at least remove the "evil" threaded muzzle.

Shortening a chrome lined barrel does not produce satisfactory long term results.

Regardless of the quality of chrome plating, firing the weapon will, in time, cause the chrome to flake at the muzzle crown. When this happens, accuracy goes down hill FAST.

I have attempted several times to achive a reliable method of chrome lined barrel shortening, including surface grinding the muzzle followed by brass ball / diamond lapping or finish grinding an 11 degree crown using a precision vertical center grinder, followed by lapping. This was done on one Israeli HB and a M-16 barrel. After grinding and lapping, the crowns appeared to be PERFECT. Yet, in both cases, micro chipping of the chrome was observed within 50 rounds fired on the FAL and 200 rounds on the AR. In both cases, accuracy became worse as more rounds were fired.

Shortening an unchromed barrel does not involve this risk. The primary down side is that the unchromed barrel will not have equal service life compared to chrome, but accuracy is usually better, and you can shorten or modify the muzzle as needed.

Some argue that corrosion resistance is better with a chrome lined barrel, but it is not a guarantee. One of the worst cases of barrel corrosion I have ever seen was a chrome lined Daewoo K2.

Chrome lining is great on SAWs or select fire weapons that may see a lot of rounds fired. For 99% of the rest of us, unchromed , properly maintained 4130 chrome moly steel will last longer than many of us and provide excellent service and accuracy.

Kerry

[This message has been edited by Kerry (edited August 30, 2000).]

[kev]

I have absolutely nothing to add other than my observation that this is THE best string I've ever seen on this or any other board. A couple of informative, well thought-out posts that answer a legitimate question. WELL DONE!!

[BB]

Is there anyone out there that can put a quality chrome-lining on a barrel for me? Metaloy?

[FALPhil]

Unless you plan to shoot lots of corrosive ammo and never clean it, OR you live in a rain forest, why would you want to? It doesn't buy you anything otherwise.

Originally posted by BB:
Is there anyone out there that can put a quality chrome-lining on a barrel for me? Metaloy?



------------------
..Phil
Download free targets at
http://harringt.home.mindspring.com/targets.htm

[BB]

Originally posted by Phil:
Unless you plan to shoot lots of corrosive ammo and never clean it, OR you live in a rain forest, why would you want to? It doesn't buy you anything otherwise.


It buys you about 3000 more rounds through your barrel.

And I might end up in a rain forrest http://www.fnfal.com/forums/biggrin.gif

[Pete2]

Originally posted by BB:
It buys you about 3000 more rounds through your barrel.

And I might end up in a rain forrest http://www.fnfal.com/forums/biggrin.gif


Considering that you can buy a couple spare barrels AND have them mounted(as needed) for the price of having your barrel individually chrome lined, the extra 3,000 rnds doesn't make economic sense.

[BB]

Ok, so Pete2 who is doing chrome-linings for $300?

[W.E.G.]

I hear the comments about degradation of accuracy. One important question is NOT answered:
HOW MUCH degradation of accuracy are we talking about?

A 2 MOA gun goes to 2.5 MOA?
Well!
Better just throw it away. Call me before you set out your trash.

If "match accuracy" is our goal, we need to dump the chrome-lined military barrel from the git-go and go with a very expensive aftermarket barrel with a custom chamber.

I'm sure somebody will disagree. But, I don't think most of the FAL crowd is looking for an MOA FAL. Look at the ammo most of us are shooting in our FALs. Milsurp! I may be the oddball. But, when I'm shooting milsurp ammo, a reliable go-bang is what it is about. Accuracy only needs to be minute-of-whitetail or minute-of-milkjug. I can't believe that the milk jug is going to be safe because of chrome-flaking.

Go ahead and cut the chrome barrel if you like the looks. That's probably why you bought that gun in the first place. Worry about the flaky muzzle when you can't hit the jug.

When it comes time to shoot matches, you will use a heavier gun, with better sights. When it comes time to hump over ten miles of ridges looking for a buck, any non-masochist will carry a lighter gun.

Have fun with your FAL.

Load and be ready...

[Fred]

I have thought about the threaded end of the barrel and how to cover up rather than cut for some time. It came to me that a threaded sleeve that is pinned to the barrel will serve two demands. First is to hide the evil threads and second to allow for a varity of different brakes to be attached by screws into the sleeve. Of course a bayonet type joint could also be used, but is up to the individual. (As far as I know, the BATF only limits the quick joint to not being threaded. After all they are comfortable with the idea of set screws for attachement so why not posts that remain always there? So this would be an opportunity to walk around the restriction.) If the sleeve was to protrude out slightly, say 0.50", then the end of the original barrel would be protected from future damage. This is similar to how many bull barrels are finished. Since the threads are now gone and there is enough meat in the sleeve to attach a brake with real screws rather than set screws then the reliability of the joint can be maintained and the user can change brakes whenever desired. I believe that a o-ring would be needed between a brake and the sleeve to ensure coupling of the propellant gases to the MB.

If the sleeve was similar to the long Steyr model, with the prongs cut off, then the damping action to the barrel will be maintained. The Steyr MB was a clever design in that it used the loose fitting of the long sleeve to act as a vibration damper to the snaking action of the thin barrel when the bullet was launched. The tight fitting MBs do not achieve this damping action. Experiments have shown that the bullet position moves about 3-4 inches at 50yrds with the only change being the MB on or off. Other MBs give different results that seem to depend upon their mass and exit hole structures.

There are times when the brake is desired and those when it is the wrong thing to do. However easy removal and attached reliability is not readily reached when using the original barrel OD, no meat to work with. So the BAFT keeps everyone over the barrel, so to speak, with a compromise solution. More importantly, a permanent decision that is hard to undo. With this solution both the BAFT and user can be happy.

[W.E.G.]

Should be easy enough to create a sleeve.

Get a steel rod of fairly hefty diameter.

Cut the rod into billets of a length to suit your design.

Drill a hole in the center of each billet.

Tap the billet to correspond to the correct thread diametter and pitch.

Use a barrel stub from an earlier shorty project to support the the inside of the threaded billet.

Chuck the billet (with the stub in place) into a metal lathe. Turn it to the diameter you desire.

Remove the barrel stub from the sleeve you just created.

Install the sleeve on your rifle.


On the subject of a "loose" muzzle attachment, I disagree with that concept. You want the barrel harmonics to be the same from shot to shot. Othewise, groups will be unecessarily large. Whatever you put on the end of the barrel should be installed to fit TIGHT.

[sturmgrenadiere]

Enough has been said, but dammit, I get home late and always get the end of good threads, but this time I am getting in...

My AR has a government issue style barrel (tapered under handguards, so it is not a heavy barrel) with an A2 compensator/flashider. It is chrome lined and shoots 1moa at 100 yards with decent reloads from a progresse. I pulled the original colt heavy barrel and replaced it with the chrome lined gov't barrel so that it shot the same as what I carry as a Marine. Now, the Remington PSS in 300 win mag I foolishly sold shot about .5 moa, but granted, it was a middle quality bull barrel that was not chrome lined, and with match rounds held that moa out to about 800 yards.

Not a comparison but a point. The accuracy lost with chrome lining is irrelevant regarding the nature and purpose of these rifles. I have a shiney new Argentine chrome lined barrel from gunthings for my FAL. I am yet to get it all sent off to the smith so I can't give you a report. My crappy Century L1A1 I had a few years ago actually shot about 1.5moa with good ammo and a steel barrel. Why did I buy chrome? Simply becasue of wear, utility, and PREFERENCE. I care for my rifles and maintain them well. I don't think I will ever be in a situation that warrents not cleaning them for an extended period of time in a very humid environment. But I like the wear factor. Granted, I am curious about this 3000 more rounda you get, according to BB. I'd like to see where that data came from since I think it ought to be a bit more with proper care. But it all depends on the nature of shooting (all rapid, all slow, mix, full auto), type of powder, cleaning, quality of the barrel to begin with, etc. There are so many factors that go into barrel wear. Chrome is great for full auto. Helps keep throat erosion down supposedly. But for semi auto rifles, it is really your preference. Don't let the accuracy loss be a factor. Could you attribute your groups opening up a 1/2 inch to the barrel and not the ammo, ambient temperature, would you even worry, etc... I would be curious if it is worth having someone plate a barrel you already have. I'd just buy a chrome one if you really want one. this argument rages on all boards and keep in mind, the reason the military went to chrome was for wear and corrosion resistance. The loss of accuracy is negligible in rifles meant to shoot people at 500 yards, not clay pidgeons. A chrome lined barrel on a FAL that shoots 2moa giving rougly a ten inch group at 500 yards is still a chest wound if aimed center of mass.

Just my Motrin and NyQuil induced thoughts...
Ben

[W.E.G.]

Chrome barrels rule when you need a gun that will need minimal maintenance in the field. I find that I NEED to clean the rest of the rifle long before I need to clean the chrome bore.

[Fred]

Gary,

Buildings have been using harmonic resonators for years to keep the windows from shattering. I am not advocating that the sleeve be loose fitting along the entire length just along the skirts behind the threaded region. I have used this solution many times to keep structures from moving when in a high vibration situation. If you have access to a shake table you will see what I mean. The idea is to keep the barrel from moving as the bullet goes down by transferring the energy to the sleeve's bell surface. The energy is dissipated as friction to the air. Many target pistols use simply a weight located on a movable rail along the barrel. However, they typically have thicker barrel walls and don't snake around as much. As the bullet goes down the barrel it is put into rotation by the rifling grooves. This rotation causes the barrel to want to twist in a similar manner to relieve the stress. Since the barrel has a non symetric mechanical load, ie. gas block, complex motion is a result. The vibration frequency(s) are a function of the steel strength, lengths involved, and other loads on the barrel. Other loads include bipod and muzzle brake. There have been patents issued that detail damping out the barrel motion by the use of energy dissipators. Of course, an optimal solution will also be a function of the driving force, ie. the bullet weight and propellent energy.

[OODA_Loop]

On threads at the muzzle - I have a letter from BATF to me responding to this issue - in brief, threads ARE allowed if something is permanently attached with threads to the barrel (i.e. muzzle brake, extension, cap) - permanently meaning silver solder that melts at 1100 F or more, or 4 equidistant tack welds, or seam weld 1/2 of circumference of barrel. All other current ridiculous rules apply as well (lugs, U.S. parts count, flash suppressor, etc.).

On chrome lined bores - I don't pretend to be a smith or expert, but my AR with a chrome-lined Colt A2 Gov't profile barrel will, with a scope and some effort on my part, produce sub-MOA groups at 100 yards from a sandbag rest - with Black Hills 55gr reloads from Kesselring's. This was a used rifle which hadn't been cleaned in years when I got it.

I live in the Pacific Northwest, so moisture is an issue here, and I know that ARs seem to need the lubricity of chrome for extraction. I suspect it provides a mild assist to FAL extraction as well.

If I was shooting a MATCH rifle, that'd be different. My attempts to build a FAL is due to the current legal situation - mil. config is fine, it's like shooting an old 98k - just like the old warhorses as is. So I'll be putting a chrome lined on the IMBEL receiver. Your milage may vary, this is just what works for me. bt

[Cosmo]

Kerry- just out of curiosity, did you ever attempt to use any sort of backing baterial to effectivly support the chrome from inside the barrel? If you would drive a long bullet done the barrel to the point where you want to cut it, the bullet would give the chrome support. Sort of like when you want to cut a board neatly, you put a piece of scrap wood under it so don't get any splintering. Just a thought.
Cosmo

[W.E.G.]

...I have used this solution many times to keep structures from moving when in a high vibration situation...

Whoa Fred! I'm clearly out of my league here. But, we do agree that the muzzle attachment has to be affixed tightly at the point of contact with the barrel.

When I used to live in a trailer, I had a roomate who could fart in the kitchen and I swear I could feel it vibrate the trailer all the way at the other end. I wish that Airstream had been equipped with one of them harmonica resonators.

Load and be ready!

[elbo]

Fred clearly didn't love ya , Gary.

[SIG552]

Now that this thread has been resurrected, can anyone tell me about an L1A1 barrel? Is it chromed? I am referring to the standard British Army barrel. Did any countries chrome their FAL barrels?
Thanks,

SIG552

[davedude]

ten inch group at 500 yards is still a chest wound if aimed center of mass.

Crap! Best I seem to be able to do anymore is a 12 inch group at 100yrds....
It's been getting a little better but progress is slow....

Shot my new to me old Savage 99E yesterday. Went thru abut 12 rounds and didn't get one on the paper....:(
Turns out the iron sights are way off, I figured out it was shooting waaaaay right and a little high at 50yrd..I ended up geting a bout a 3inch group at 50 yrds on the target to the right of the one I was aiming at and put the gun up for the day.

uh...oh yeah...."chrome"

Dave Dude

[Radio]

Dang, I actually remember this original thread! Old age!!

Fred doesn't hang around much anymore. Sorta like me.

What I would have liked to read was an expansion by Kerry on his accuracy -vs- microfracturing position. Sadly he hasn't been around here in over four years. Anybody else wanna step up to the plate?

After that, all we would need for Jeter is a weigh-in by that fellow (saw it yesterday but can't remember his name) with the signature, "I fart, therefore I am."

--Radio

[W.E.G.]

Originally posted by Radio
After that, all we would need for Jeter is a weigh-in by that fellow (saw it yesterday but can't remember his name) with the signature, "I fart, therefore I am."

I'm sorry it has come to this.

http://www.youtube.com/watch?v=93U5ctngqF0
(episode 6)

[Bugs]

Which FAL barrels (OEM) were manufactured with chrome lining and which were not?

[Stranger]

Originally posted by Kerry

Regardless of the quality of chrome plating, firing the weapon will, in time, cause the chrome to flake at the muzzle crown. When this happens, accuracy goes down hill FAST.

I have attempted several times to achive a reliable method of chrome lined barrel shortening, including surface grinding the muzzle followed by brass ball / diamond lapping or finish grinding an 11 degree crown using a precision vertical center grinder, followed by lapping. This was done on one Israeli HB and a M-16 barrel. After grinding and lapping, the crowns appeared to be PERFECT. Yet, in both cases, micro chipping of the chrome was observed within 50 rounds fired on the FAL and 200 rounds on the AR. In both cases, accuracy became worse as more rounds were fired.


I don't believe it for a minute. Please, provide some proof in the form of pictures or better yet, an article or link to an article.

[mn]

I have shortened several AR chromed barrels (Bushmaster & DPMS) and with many thousands of rounds through them have yet to see any reduction in accuracy. The worst is still at the 2-1/4" @100 yards and the best are still under 1", with one hanging around 1/2." These are 10 shot groups with decent ammo, usually my loads with 50 and 55gr V-Max or 52gr. Sierra Match, lowers with match triggers, and reasonably good bench technique. A quick look with a 10X loupe shows no flaking; the muzzles still look like the cut off sections. In this limited sample, there seem to be no problems.

[hagar]

When a chrome lined barrel goes bad, they go very bad. Friend of mine was shooting highpower with a Bushmaster chrome lined barrel, and at about 8000 rounds he was lucky to hit the target all the time at 300 yards, and 600 was an absolute disaster. It actually shot pretty well before then for a non competition barrel.

[odin75]

Anyone have any feedback on the FN hammer forged chrome lined heavy Israeli barrels DSA is selling?

Greg in FL