AR10 on .308/NATO Barrel: Length? Fluted vs. Bull?

[GS455]

A buddy of mine is getting ready to put together an AR-10 in the thinking about barrels. Fluted versus bull? Length?

Pretty much an all-around range toy. Our range currently goes to 400 but would like to see what he can do to rival the performance of his .308 RPR. Maybe out to 800 or 1,000 one day. Not looking for $1,000+ Barrel or anything uber boutique but just best, typical Barrel application.

 

[WasNH4X]

https://www.shilen.com/LFARBarrels.html not what you asked about ,however ,I have two heavy varmint barrels ( 6.5 creed ,22 Nosler ) that shoot small . You can contact dtech uppers , he will probably fix you up with "bull" with headspaced bolt . Range toy, I'd go 24" for the fps , not a fan of flutes . I like HEAVY as I'm only carrying from truck to bench .

 

[bigjake83]

20" is the sweet spot for .308 and .223, for balance, Muzzle Velocity and Barrel Harmonics.

 

[WasNH4X]

20" is the sweet spot for .308 and .223, for balance, Muzzle Velocity and Barrel Harmonics.

Having seen some of your builds groups , I'll not argue. Should I put together something in the 20" range, just for the hell of it, I'd go the Virgil King route of 21.75" , 1" diameter

 

[FredHammer]

I've got a 20" Ballistic Advantage Bull barrel that bugholes regularly.
Fluted barrels need to be deeply fluted to be beyond cosmetics, and even then the deeply cut will cast barrel heat mirage more and quicker. I'm done with fluted barrels.
800-1000yd 308 AR10 is a chore. 7-08 makes it happen with less frustration. Even the 6.5CM would be better.

 

[WasNH4X]

800-1000yd 308 AR10 is a chore. 7-08 makes it happen with less frustration. Even the 6.5CM would be better.

Hence my suggestion of going 24". Own 2 308s ,bolt & gas 16" barrel ,fps is sloooooow . In agreement, that 6.5 would be easier .

 

[bigjake83]

Having seen some of your builds groups , I'll not argue. Should I put together something in the 20" range, just for the hell of it, I'd go the Virgil King route of 21.75" , 1" diameter

20"-22" is fine, and yes if 6.5CM is a option I'd go that route.

If you go 6.5CM stay away from anything longer than 18" with a rifle length gas system and make sure your bolt of choice is a HP Bolt with the small .58-.60 firing pin.

As a standard starting point I run 18" RLG, 20" RLG +1, 22" RLG +2 at the very least.

You can go +2 on 20" and +3 on a 22" if you want but I don't notice any difference when running H2-H3 Buffers and Full Mass Carriers with a AGB.

 

[wade2big]

Snip…

You can go +2 on 20" and +3 on a 22" if you want but I don't notice any difference when running H2-H3 Buffers and Full Mass Carriers with a AGB.

I bet the difference would come into play when/if shooting suppressed.

 

[WasNH4X]

@bigjake83 I put together a 6.5 CM upper 4-5 yrs ago. Used the suggested heavy varmint above, 24" ,4 groove. Shilen suggested using an adjustable gas block ,I didn't , but haven't had any function problems whatsoever. Have no idea of gas tube length or firing pin size in supplied bolt with barrel. Just pinned it on dpms lower and went to shooting sub moa with Hornady 140 match ,got ejector swipes. Worked up handloads ,40.5 grain H4350 ,44 grain superformance , 142 smk ,sub moa ,with the H4350 load smaller by a tad,no ejector swipes. I'm a happy camper. Going to experiment with some 130s this year , "just to see"

 

[Jsp556]

I’d look at Criterion or the one of the RTR options from Craddock Precision.

I’ll be the contrarian here and suggest a 16” or 18” with rifle gas. All my 16 & 18” rifle gas guns have a smoother recoil impulse and easier on brass than my 20 or 22” guns. A 16” large frame will be about the size of an 18” Ar15 and usually weigh at least a pound more. That’s not too unwieldy for walking too and from deer stands or location to location while predator or hog hunting. The short guns are a lot easier to get in and out of our side by side and Jeep. If it’s only going to be a bench gun or shoot from an enclosed blind, where mobility isn’t a factor go with whatever.

 

[bigjake83]

I bet the difference would come into play when/if shooting suppressed.

Yeah I need to get off my ass and buy a couple Cans so I can further test my builds under harsher condition, I've just always looked at Suppressors solution looking for a problem.

I've got a couple lowers (1) Large/ (1) Small Frame I'm SBRing so I can test the short barrels without P&W or using AR Pistals.

 

[bigjake83]

I've also got a bunch of the Craddock RTR barrels coming next week so I'll be covering them soon as well.

 

[Jsp556]

I've also got a bunch of the Craddock RTR barrels coming next eek so I'll be covering them soon as well.

I’d rock one of those 14.5 308 barrels but I don’t have a SBR’d lower and hate pinned muzzle devices.