Nitrocarburized 20" 4150 Barrel

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GlockFu

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After doing a ton of research I think I want a Nitrocarburized 20" 4150 Chrome Moly Barrel. Does anyone know who makes a good one? Also, if this is not a good idea, please let me know why.
 
Just curious, but what benefits do you see in getting a Nitrocarburized barrel?
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The reason for a Nitrocarburized barrel would be to get the durability of a chrome lined barrel but retain the accuracy of an unlined chrome moly barrel. I want a 20" for accuracy at long distances but don't like that stainless is not as corrosion resistance and wears much faster.

i think cmmg and dsa both use that process. Haven't seen that many twenty inch cmmg barrels.
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CMMG just changed to Cold Hammer Forged but they are still chrome lining their barrels. The WASP lined might be nitrocarburized but they use 4140 steel for some reason (maybe because it's cheaper?).
 
I have seen the nitro barrels in 14.5-16", but nothing in a 20". You might consider getting a barrel that you like and the process done to it.

Melonite contact:
Rodney Lanier
MMI-Tru Tec, Inc.
2609 N. 12th Ave.
Paragould, AR 72450
870-236-6920
[email protected].
 
Not assuming anything, but unless you're trying to shave another .001" off your groups, the difference between chrome lined and nitrocarburized isn't going to be enough for you to notice one way or another.

Are you a long range bullseye competitor or someone who routinely shoots sub-moa groups with your rifles? If you're not, you probably don't really need the added expense of a special barrel.

As far as durability and corrosion resistance, it's hard to beat chrome lined but with proper maintenance and care, even a steel barrel in the white won't have problems. A standard Chrome-moly barrel, lined or not, shouldn't rust as long as it's properly maintained. I live in Tallahassee, FL where humidity hovers between 80% and 100% year round and I'm 45 minutes from the ocean on two sides, and 3 hrs inland from the other side (obviously land to the north), I've never had a problem with rust except on a Remington 870.
 
Not assuming anything, but unless you're trying to shave another .001" off your groups, the difference between chrome lined and nitrocarburized isn't going to be enough for you to notice one way or another.
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So are you saying that the difference between an unlined Chrome Moly barrel and a Chrome Lined barrel is .001" difference in accuracy?
 
GlockFu said:
So are you saying that the difference between an unlined Chrome Moly barrel and a Chrome Lined barrel is .001" difference in accuracy?
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I wasn't speaking in exact terms, it's probably fairly more than that. It's my experience through shooting countless rifles with various barrel types that chrome lined barrels are capable of around 1moa, with the higher quality, more uniform plating jobs (higher end barrels) resulting in as good as .6moa or thereabouts. Chrome-moly barrels are capable of sub-MOA accuracy at the cost of much faster wear and less corrosion resistance. Accuracy falloff happens much faster with these barrels.

What I'm saying is that unless you're a bullseye shooter, police sniper, or someone else that already has the skills required to make 100 yard and greater one hole groups and you're either not planning to shoot a lot or you can afford to replace a barrel every year or two (or more often depending on how often and how much you shoot, as well as how fast you shoot and how hot you let your barrel get), then it's probably not worth the extra cost involved (ie someone that goes through 10k rds a year or more, vs someone that shoots a few mags every month or two). If you shoot less and want the .4" or less difference in group size at 100yds, then it's a good idea. If you shoot a lot of rounds, rapid fire often, and don't need a dime sized group at 400 yds for a real purpose, then it makes more financial sense to get a chrome lined barrel that may have marginally less inherent accuracy, but will last MUCH longer, retain accuracy longer, and be easier to clean and maintain.

FWIW, this is just my opinion based on my own experiences and what I've read. I can't outshoot a chrome lined barrel at 100 yds so I have no pressing need for an extra few tenths of an inch (my best is 1.45" group with an AR). I also (used to) shoot a lot, and prefer the durability of a chrome lined barrel.
 
Here's the closest thing I know of, in a complete upper:

http://www.dsarms.com/DSA-ZM4-A3-Up...SZM4CBU20FLUTED/productinfo/DSZM4CBU20FLUTED/

I believe those are 4140 steel, not 4150. Incidentally, when using the nitriding/nitrocarburizing surface treatment, there is less benefit to the 4150 steel because the 4140 steel will actually take the nitride-hardened layer to a greater depth than the 4150. The 4150 might still have a benefit if you intend to keep shooting when the barrel temperature is past 800 degrees F.

The other companies I know of using nitride treatment are S&W, CMMG, LWRC, and on just one or two models each, Bushmaster, Remington, and Spike's. I don't know of a 20" nitride-treated offering from any of those.

The nitrocarburizing treatment does appear to provide the benefits you're expecting and there is no reason not to buy one - but a high quality chrome lined barrel (especially CHF) will probably have accuracy that is indistinguishable outside a laboratory setting. The major benefits of the nitride approach are cost and all-over corrosion resistance. It also slows gas port erosion, but that usually isn't an issue with 20" barrels.
 
DSA Arms is not that great in quality is it? I hear they are fairly spotty but they do have what I'm looking for. So it doesn't look like anyone really makes what I'm looking for so who would you recomend for a accurate 20" chrome lined barrel?
 
What have you heard about DSA quality? They've had a recall on some FALs (less than a year of production), and some minor issues here and there, but on the whole are quite good. I own one of their 16" ZM4 uppers with a nitrided barrel, and also a couple of their FALs, so I have some basis to go on. I wouldn't hesitate to get the upper I linked to, as long as you aren't expecting sub-MOA accuracy.

If you want high precision, I would go straight to a quality stainless barrel, and there are many to choose from. A good stainless 5.56 barrel should go at least 5-6000 rounds of top accuracy, possibly 10,000+. That's a lot of shooting.

If you want chrome lined anyway, Palmetto State Armory has offered a 20" rifle barrel that is cold hammer forged and apparently made by FN - that is probably the best chrome-lined 20" AR barrel you will find. Other good options would probably be BCM and Armalite. Not a whole lot of companies are making 20" chrome-lined AR barrels right now, as you probably know.
 
dsa

DSA isn't a spectacular deal, but they are a decent one. I've really enjoyed my upper but with only 800 rounds down the pipe i can't say they are the be all end all.

I tend to shoot better with the zm4 midlength than i did with an m4. I think that has more to do with sight radius than inherent barrel design.
 
BCM offers 410 stainless barrels. They provide longer life than the typical 416 stainless that most stainless barrels are made of.


As for corrosion with a stainless barrel... you would have to abuse a stainless barrel to get it to rust. Above and beyond salt spray....
 
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