your thoughts on chrome lined barrels

j427x · 05-07-2009, 10:29 AM

i have been playing with the AR-15 platform for going on 30 years now.

my first experiences with it was -like most folks from my first joining the service.

the first weapon i was handed was a colt m-16a1. it looked like it had fired 10,000,000 rounds! loose as a goose! and prone to jamming. the barrel had about a 4 inch patch of chrome bore lining stripped off near the gas tube port. in that area the rifle grooves were very, very week.

the odd thing though was the rifle still shot OK. it could print a three shot group on the short zero one on top of the other. but i digress.

my question of the day is

is chrome lined bore and chamber really all that important?

all my 5.56 AR types to date have chrome bores and they have no problems with function on about any ammunition. even the russian steel cased stuff.

my only non chromed barreled ARs are of the 7.62x39 type. i have an old colt and am building a del-ton carbine. the old colt has fired maybe 500/600+ rounds of mixed 7.62x39 ammo with no problems that wern't from mags. i have even fired some corrosive yugo brass ammo through it. after a quick clean up with windex/hot soapy water/ hot water and then a lube down it cleaned up real good. took only a little more effort than my AK's after a big dose of the old commie corrosive stuff. i also have a yugo AK

so my experience so far with the non-chromed lined bores is good overall but i haven't fired but a fraction of the ammo.

so far i still prefer the chromed barrels but with things being so scarce, backordered for up to two years i took the plunge and bought a del-ton middy no-chrome because it was close to what i wanted and in stock at the time.

has anybody had problems with a non chromed 5.56 barrel due to it not being chromed?? like feeding problems. rounds sticking in the chamber and the like?

yarro · 05-07-2009, 07:53 PM

Give equal quality of finish in manufacturing, on average a non-chrome lined barrel will be more accurate. This is due to variation in plating thickness and the fact that chrome is deposited at a different rate on corners than on flat areas. Now, chrome cleans up much easier and faster than chrome-moly steel. The throat and bore should last 2x longer on average. Stainless steel barrels clean up easier than chrome-moly steel and usually suffer throat erosion at a lesser rate. High end hand lapped barrels are easy to clean no matter what they are made of. My Noveske SS and other handlapped barrel on my shorty cleans up as easy as my FN chrome lined barrel and due to surface finish in both takes a lot longer to get to the same level as fouling as the chrome lined one. My chrome-moly is never cleaned to the point that a patch won't have some color. I did that once and it took so much time it made me not shoot it for six months. Almost clean shoots just as well. My FN barrel is A1 profile and strings as it heats up as does my unknown mfg chrome-moly, both differently. The the high end match ones don't. My best guess being that they were never straightened during production so don't have the residual stresses in them. Noveske makes two chrome lined barrels. One is a light weight and I don't recall what the other is.

On my M16 shorty, I had nothing but trouble from any chrome lined barrel that was not a GI barrel as commercial chambers with chrome lining were all too tight. So I had a used chrome-moly of unknown mfg on it and it went 35-40k rounds just from me before I replaced it due to throat erosion. It still shot 3-4 MOA, which allowed me to hit a man sized ringer at 320 yards , but I really just needed an excuse to reconfigure the gun into something more modern looking. I replaced it with a 12.6" stainless match barrel built by Randal at ar15barrels.com and it runs fine and shoots 2-2.5 MOA with Brit SS109 and 1-1.5 MOA with my generic 62gr reloads that I haven't bothered to try tuning to the gun. I shot a slightly less than 1 MOA 10 shot group with it shooting Black hills 77gr match ammo at 300 yards on a rare dead calm day. The FA trigger sucks or it would probably been better as it took me five tries not to get at least one flier do to me hosing a trigger pull. I want to build an SBR with a good trigger to play with.

-yarro

nalioth · 05-07-2009, 08:24 PM

yarro hitis it on the head, but you have to consider that for any of those issues to appear, you'd have to fire 50,000+ rounds.

Are you gonna stress your AR15 to that point?

j427x · 05-07-2009, 08:32 PM

i haven't heard about the under-size problems with non gi chromed barrels as all my chromed barrels are supposedly GI steel/pattern and so forth.

i would think that the problem has been corrected with commercial made chrome lined barrels by now surely?

i did shoot someones armalite last year which has a non gi type chromed barrel it shot very well as best i could tell anyway. i will be the first to say though they may not all be the same.

30 to 40K out of a plain steel 4140? gees that is a bunch. some of our m4/m5 barrels were pretty shot out by about 5,000 to 7,000 rounds but they did see much abuse and mostly the mk262 ammo. this makes me feel better about my non chromed middy i just picked up!

allesennogwat · 05-08-2009, 04:06 PM

The M-16 doesn't have super strong extraction. A pitted chamber and the high pressure 5.56 can be a problem. Stainless steel can help. Hard chrome will wear the best. Somebody gave me a non-chrome 16" standard weight no-name barrel in part of a trade. That barrel works surprisingly well. I wouldn't buy a non-chrome barrel unless it was for a match rifle.