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Mil-Spec Barrel Recommendations?

2K views 13 replies 10 participants last post by  noFanku 
#1 ·
I'm trying to piece together parts for a new mil-spec 6.8 upper (or uppers) and I'm having some trouble finding appropriate barrels in-stock. I thought I'd ask for advice about where I might find a barrel. I'm posting this because it seems that many of the "tactical AR" suppliers that are supposed to offer them seem to have dropped the caliber in the last year or so, and they seem to be focusing on 5.56, .300 BLK, 6mm ARC and 6.5G instead. It seems that most of the links that I follow to various AR builders and barrel companies come up empty when I limit the searches to 6.8 barrels only. When barrels are available, they seem to be limited to stainless target/hunting applications rather than the military applications for which the 6.8 was originally intended.

Here's what I'm interested in:

* Combat rifle setup, with old-school fixed front sight (carry handle upper or + flat-top with F-marked iron sights). I'm not really interested in a low-profile gas block, a free float rail system, a rail-mounted front sight, or an optic -- though that seems to be what everyone is offering in the current market.

* Gas block journal long enough to accommodate the fixed front sight (which is longer than a low-profile front sight block). Prefer to have the barrel maker pin the FSB in place as I don't have the required jig for precision alignment and don't want to trust the job to local gunsmithing. Iron front sights must be taper pinned, no set screws.

* CHF / Chrome lined / MPI. Not stainless or nitrated 4150.

* Barrel lengths 12" to 18". Interested in both thin and heavy barrel profiles +/- fluting.

This is a proposed caliber conversion for an M16 currently uppered in 5.56 that will not see semi automatic fire. I'm not particularly interested in recommendations for target barrels, or low round volume configurations for hunting applications, which would burn out quickly. Though I might be willing to consider those for an future AR15 build, this upper build needs to be able to support the type of hard military use that the 6.8 was originally designed for.

Any info on mil-spec 6.8 barrel availability?

Thanks.
 
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#2 ·
You've constrained your options to the point that you are probably going to need to look for a used barrel. The Daniel Defense S2W barrel is the only CHF CL barrel I can think of off the top of my head but they are out of production. Looks like McGowen Precision can make you a 4150 CmV barrel to your liking....I don't know if they are CL. I believe PSA might have had FN run some 6.8 CL barrels a while ago. The dream barrel for you would be the Colt SOCOM 14.5 in 6.8, but no such thing exists (and if you don't have one in 5.56 you should consider it given your stated preferences).

That said, I think the ARP Scout barrel would serve your purposes very well, but it's nitrided. You aren't going to see any benefit of CL over Nitride unless, maybe, you expect to be firing full auto for sustained periods. And if that's true, you'll have enough money to buy a few of them. They are consumable items at the end of the day. It seems like you are going out of your way to build up a configuration that those who use weapons for a living have moved away from over the past 20 years of combat experience. If that is for nostalgia's sake, then so be it (I have an A4 in the safe just to remind me of my days carrying an A2), but if I was going to take a 6.8 SPC rifle into harms way I would likely choose an LMT monolithic upper with one of their exceptional barrels.
 
#3 · (Edited)
That said, I think the ARP Scout barrel would serve your purposes very well, but it's nitrided. You aren't going to see any benefit of CL over Nitride unless, maybe, you expect to be firing full auto for sustained periods. And if that's true, you'll have enough money to buy a few of them. They are consumable items at the end of the day.
You are right -- barrels, ammo, feeding devices, parts and even the receivers are all consumables.

You've constrained your options to the point that you are probably going to need to look for a used barrel. The Daniel Defense S2W barrel is the only CHF CL barrel I can think of off the top of my head but they are out of production.
I had thought about that, but I did not realize that the availability problem for 6.8 SPC barrels was already as bad as it is. I have to admit that I haven't been paying attention to 6.8 until now. Although there seemed to be a number of milspec suppliers for 6.8 barrels the last time that I looked, my lack of attention to 6.8 while it's market has changed has caused me to miss the boat. I guess that what some people have been saying is true -- the 6.8 SPC is dead in terms of military applications, and the proof is the disappearance of milspec barrels in the marketplace.
 
#8 ·
Have two uppers used 14.7" FN CHF melonite 4150 barrels that live on select fire lowers. Installed F front sight towers without significant issues and the hard steel combined with melonite has more durability than some of my chrome lined barrels have and both get run till glow a nice cherry red. Can still find the FNs around.
 
#10 ·
I am not really sure what is meant when they say they are looking for a Milspec 6.8 barrel. There are no military specs for a 6.8 barrel. If you want one that mimics a 5.56 barrel then it would be cold hammer forged, phosphated finish, chrome lined and 14.5 or 14.7 inches long (don't remember which). The whole milspec term is used way too loosely in my opinion.
 
#11 ·
As Woodstock said if never officially adopted by the military how can there be a milspec barrel? The closest thing I found to milspec IMHO were the 14.7"FN CHF 6.8 spc double chrome lined barrels military used in their initial trials. A lot of these with melonite treating were sold by PSA by the gazillions. I would add two to six to my cart when they ran them on their daily deals as preferred melonite and 16" is my least favorite barrel length on AR 15s. Give me a 13.7", 14.7" then pick back up at 18" and 20". I also prefer melonite to chrome and have burned more 6.8 in select fire than most.

16" seems so popular to me just because the BATFE chose it as their arbitrary legal rifle length. I would rather pin a 13.7" or 14.7" for a defensive carbine then jump to 18" or longer for varmint/target/SPR/DMR use. Have built six to date, two with suppressor adapters, two with flash cans and two with standard bird cages. Still have at least four in the parts locker. See lots of the melonite and chrome FNs still out for sale. Google will find 16"s easily and 14.7"s with a little more work.

A proprietary blend of Hammer forged chrome molly vanadium made by FN that is referred to as "Machine Gun Steel" by virtue of its use in FN's M249 and M240 weapons. The hammer forging process work hardens the steel, making it more durable. In addition, the chrome process for the bore allows for a lining almost twice as thick as a standard M16 for enhanced durability. Chambered in 6.8 SPCII, with a 1/11 twist, M4 barrel extension, and a Mid-length gas system. Lighter profile barrel has an A2 profile under the handguards and just enough material removed after the FSB. Barrel is Mil-spec phosphate coated, High Pressure tested and Magnetic Particle inspected, and finished off with an F-marked front sight post with sling swivel, standard handguards and a an A2 flash hider. The 14.7" barrel allows for an A2 length flash hider to be permanently pinned to bring the barrel to minimum legal length, instead of more expensive, extra long length flash hiders. The flash hider is pinned and welded.
Pair of mostly matched 14.7" FN CHF 6.8 melonite builds, add 2" and become unwieldy in tight quarters:



 
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#14 ·
As Woodstock said if never officially adopted by the military how can there be a milspec barrel? The closest thing I found to milspec IMHO were the 14.7"FN CHF 6.8 spc double chrome lined barrels military used in their initial trials. A lot of these with melonite treating were sold by PSA by the gazillions. I would add two to six to my cart when they ran them on their daily deals as preferred melonite and 16" is my least favorite barrel length on AR 15s. Give me a 13.7", 14.7" then pick back up at 18" and 20". I also prefer melonite to chrome and have burned more 6.8 in select fire than most.

16" seems so popular to me just because the BATFE chose it as their arbitrary legal rifle length. I would rather pin a 13.7" or 14.7" for a defensive carbine then jump to 18" or longer for varmint/target/SPR/DMR use. Have built six to date, two with suppressor adapters, two with flash cans and two with standard bird cages. Still have at least four in the parts locker. See lots of the melonite and chrome FNs still out for sale. Google will find 16"s easily and 14.7"s with a little more work.



Pair of mostly matched 14.7" FN CHF 6.8 melonite builds, add 2" and become unwieldy in tight quarters:



Where might one find one of these FN barrels? This is right up my ally.
 
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