In terms of semi auto AR usage which is better Stainless or Chrom Moly

dvdcrr

New member
When it comes to semi auto plinking, hunting and non heavy usage which barrel is going to last the longest round count with good rifling for an AR-15. Is it standard chrome moly or stainless? I am assuming its 4150 or 416R? I am talking just about 20-100 rounds a shooting session and not getting real hot.
 
Chrome moly will typically last longer if it is also chome-lined. If it is not chome-lined, I belive stainless will out-last it.

If anyone knows better, please correct me if I'm wrong!
 
Cold hammer forged, chrome lined barrel will last the longest. From what I understand, only FN and Daniel Defense make CHF CL barrels for AR15s in this country. FN uses the same blanks they use for the M249 SAW.
 
A 4150 CMV barrel well last longer than a 416r stainless barrel. The 416 may initially have a minor accuracy edge.

For 99.99% of civilian shooters it makes no difference.
 
It kind of depends on how you define "last" in terms of round life.

If you are talking match grade accuracy the Army Marksmanship Unit pulls barrels every 700 rounds. Most civilian match shooters pull them between 1500 and 2500 rounds.

Insofar as military requirements for a battle rifle production barrels are required to go 6000 rounds at a prescribed firing schedule. The M16A1E1 (adopted as M16A2) was required to go 12,000 rounds by the Marine Corps and they did so firing genuine Belgian SS109 ammo.

I have a sectioned barrel from a gov't test fired at unknown schedule with 20,000 rounds on it and it is missing most of it's chome.

I am aware of a set of M16A1s that were subjected to round counts in the Marine Corps and they all had 40,000 rounds on them.

Acceptance groups for new M16/M4 is 4.5" at 100 yards and rejection is 7.2" at 100 yards with ball ammo. To a match shooter this is not acceptable as they want a barrel that will shoot 1" or less. Thus it depends on your definition of "last".

It it is just gonna be shot at cans etc and not used for match shooting it is a moot point whether it is CM or Stainless.

There is however one barrel I am aware of that should go many thousands of rounds without a drastic degradation of capability. Check out http://www.superiorbarrels.com/

Especially read the sections on their testing running them in 100 round burst on a M16 lower.

I have three of their barrels and they are IMHO opinion the way to go for long life in a match barrel. It is unknown how long they will last as no one has taken one out yet that I am aware of.

At this time I have five ARs. One is a Colt Pre Ban set up as a NMA2 with 9 twist Delta Elite barrel with about 75 rounds on it. The other is a RRA 24" Varmint EOP that is unfired I have decided to sell as I have not shot it as yet as I know neither of these will last that long as a target grade barrel.

I have one built up as a NMA2 and the others have Daniel Defense 14" 4 rail handguards with 16.5 and 20" barrels. All three are the heavier barrel variety and not the milspec contours. All three uppers were built by them as they have a very unique way of setting them up.

As a rule of thumb the heavier the bullet you use the shorter the barrel life will be.
 
I think Hummer70 nailed it there. As he said -- it depends. Some people are against chrome due to possible accuracy degradation and have turned to nitriding. From what I've seen, nitrided barrels seem to provide the best of both worlds. Time will tell though I suppose.
 
The potential for inaccuracy using a chrome lined barrel is real. Chrome lining requires oversizing the bore and plating it back to dimension. That electrolytic process has to deposit exactly the right amount of build up to within .0005" of an inch. In practice and observation, it gets close, but when airgauged, the variances become significant. Most milspec barrels on the market aren't high precision simply because of the 2MOA standard.

When competition or high accuracy is needed, getting all the deviance out of the barrel bore means the industry settled on a stainless alloy with precision button rifling they can control during the process. Those barrels airgauge much more accurately, to the point the maker will offer a money back guarantee. He's putting his money and work ethic on the line with that much confidence.

As far as chrome is concerned, it's really just the cheapest mass production solution for erosion and corrosion control. That doesn't make it the best or most long lived. Military rifles that shoot large quantities of full power ammo magazine after magazine in harsh environments have been largely hammerforged nitrided for over thirty years - from European makers. It's a production cost situation negotiated with Colt that continues our lagging adoption, along with the high cost of a barrel hammer forge machine. That's changing - most commecial handguns and sporting firearms get hammerforged, and have for quite some time. Remington, Ruger, FN, and more make most of their lineup in hammerforged.

It's just the AR fans who don't notice it, protected in the cocoon of Colts contract.
 
A Melonite (ferritic nitrocarburizing) treated carbon steel barrel will last longer than either a stainless or a hard chrome plated barrel. There are some complete ARs, uppers, and barrels available that have melonite treated barrels inside and outside.

As mentioned previously, chrome plating a barrel requires the manufacturer to take into account the dimension change from the plating. Melonite is a surface hardening treatment that does not change the dimensions as it penetrates into the metal.
 
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