Best barrel length for 308 out to 400 yards?

K

KCode

Sergeant of the Hide
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Mar 25, 2019
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#1
Looking for most terminal damage with velocity but also would like maneuverability since it won't be just a bi-pod gun. Max range will be 400 yards with a LPVO. And will also have the ability for hand loading with SMK.

I'm thinking 16" but I'm open to what others think.
 
#2
16-18" seems reasonable. Ryan on the Vortex Nation Podcast talks about his Tikka set up nearly identically to what you're wanting in episode 293.

I've tossed around the idea of a 14.5" bolt .308 with a P/W suppressor adapter. Seems like a fun gun.
 
#4
I have 308’s in 16”, 18.5”, and 20”. I’ve shot all out to 600 yards, but not on game. You would need to know the velocity at 400 and make sure you have enough velocity to reliably expand whatever hunting bullets you were using.

Is this a bolt gun or AR and will you be using a suppressor?

In my experience, 18” is the sweet spot for out to 400. It’s got a bit more juice than a 16”, less muzzle blast, still very handy, but not too long when suppressed.
 
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#5
KYAggie said:
I have 308’s in 16”, 18.5”, and 20”. I’ve shot all out to 600 yards, but not on game. You would need to know the velocity at 400 and make sure you have enough velocity to reliably expand whatever hunting bullets you were using.

Is this a bolt gun or AR and will you be using a suppressor?

In my experience, 18” is the sweet spot for out to 400. It’s got a bit more juice than a 16”, less muzzle blast, still very handy, but not too long when suppressed.
Click to expand...

It's an Aero M5 lower and upper, I will be putting a barrel in them. I guess 16" would be midlength and 18" would be rifle length huh?
 
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#10
BCP said:
A 16” 308 with 150gr bullets is enough for anything you would realistically do with a 308 carbine.

The only real advantage I can think of would be 18” Hbar rifle gas, the extra weight and gas system design makes it smoother shooting off a bipod or pack imho
Click to expand...

I really like the idea of 16" handy 308 but boy does a 18" Hbar barrel sound nice and accurate...Plus rifle gas vs midlength gas. Wouldn't the 18" be less likely to beat itself to death?

I should start looking into barrels. I haven't even really started.

Edit: Does WOA not make 308 barrels? Or am I blind?
 
#11
I have a LMT 308 with a 16 inch and 18 inch barrels. Out to 400 max, I would probably go 16 inch unless you are shooting smaller critters out at that range. As long as you have the gas optimized, the mid-length isn't significantly worse than the rifle length to manage.
 
#13
ToKeepAndBear said:
If you want to put a longer barrel on your AR10, I would consider a Proof Carbon barrel to keep it less front heavy. I have a Proof Carbon 22" 6.5CM on another AR10, it's pretty nicely balanced with the carbon barrel.
Click to expand...

That's WAY over my budget. I love the idea of them but $1,000 for a barrel isn't even worth thinking about for me.
 
#15
Whatever barrel you buy, get an adjustable gas block. SLR makes a good one, but if you can stand the extra weight, get a Riflespeed. I have three of them and they just flat out work and you don’t need a special tool to adjust them.

My 16” is a 2A Xanthos lightweight build. It has a Faxon Gunner weight barrel and I got lucky; it’s a 3/4 MOA gun with 168 FGMM. Several years ago I used it to qualify on our 600 yard range and the RO in charge was sure it wouldn’t be accurate enough. Boy was he wrong. Within 5 min he turned me loose shaking his head mutter something to the effect you don’t see that everyday. There were two other guys with bolt guns trying to qualify that day that had no idea what they were doing. That gun weighs 5.9 pounds empty with no optic. It has a lot of titanium parts in it.
 
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#17
If I was limited to 400yds with a .308 AR, I would go somewhere in the 10.5” to 14.5” range. 12.5” is already getting pretty long when you suppress it.

I have a Savage MSR-10 with a smaller receiver set that feels like an AR-15 I’ve been thinking about doing this with, but it’s just not a priority for me. If it was going to be a practical grab-gun, I would make it really short and suppress. It’s 16” right now.

12.5” spitting a 168gr ELD-M at 2326fps keeps it over 1800fps out to 350yds.

12.5” spitting 138gr Hammer-HT at 2600fps keeps you within expansion out to 500yds I think.

168gr ABLR will expand well past 400yds.

Something like this is more maneuverable than a 16” AR-10:

iu
 
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#18
LRRPF52 said:
If I was limited to 400yds with a .308 AR, I would go somewhere in the 10.5” to 14.5” range. 12.5” is already getting pretty long when you suppress it.

I have a Savage MSR-10 with a smaller receiver set that feels like an AR-15 I’ve been thinking about doing this with, but it’s just not a priority for me. If it was going to be a practical grab-gun, I would make it really short and suppress. It’s 16” right now.

12.5” spitting a 168gr ELD-M at 2326fps keeps it over 1800fps out to 350yds.

12.5” spitting 138gr Hammer-HT at 2600fps keeps you within expansion out to 500yds I think.

168gr ABLR will expand well past 400yds.

Something like this is more maneuverable than a 16” AR-10:

iu
Click to expand...

I've read that the shorter barrel lengths, especially carbine gas system absolutely beat the large frame AR's to death. Plus at those barrel lengths I think 300 blackout would do just as good. Maybe I'm wrong though
 
#27
Honestly go for the longest you can get. If your not packing it around you don't need the handiness. Faster bullet means less chance of bullet not opening up at longer range. Faster bullet will buck the wind better than the same bullet at lower velocity. Less blast in the face than a shorter barrel. The ultra short barrels have a place but it has become more a fad and status symbol than practical use for many people. Remember METT-TC
 
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#28
KCode said:
Who makes one? I haven't found a 16" rifle length
Click to expand...
Off the top of my head? Criterion. There's more but I haven't followed the market close enough to commit them to memory.
Any custom shop will do it though. Catch X-Cal or someone similar on a holiday weekend like this and it won't be much more expensive than an off the shelf barrel.
 
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#29
KCode said:
I've read that the shorter barrel lengths, especially carbine gas system absolutely beat the large frame AR's to death. Plus at those barrel lengths I think 300 blackout would do just as good. Maybe I'm wrong though
Click to expand...
I would run a Bootleg Adjustable Gas Carrier and have the port cut small for 100% suppressed use. You can choke the gas appropriately and manage the cyclic rate that way.

300 Whisper will not touch the .308 for velocity with any of these projectiles even if you go 16” with it. But I do agree .308 is a bit much for case capacity and such short barrels, however, it’s what it takes to move those bullets at the speeds it does.

This was something I had planned to do for decades, but Grendel ruined those plans for me. So much more efficient and no need to depart from the AR-15 frame, no crazy muzzle blast or recoil, lightweight.

I’m a huge AR-10 guy and have been since the 1980s, and I've been buying them and shooting them for close to 30 years now.
 
#30
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#36
KCode said:
Building an AR is most of the joy IMO. Thanks for the link though.
Click to expand...

Who's platform are you planning on using ?. People talk about short rifles and then hunting , I've never quite figured out WHY ?.

Cartridges perform optimally in specific length of bore , a .308 as an example Minimum 22" IMO . Now Optimal 26.5" ?.

Now for all intent and purpose running a 168 gr. out of 22" barrel is gonna put one around 2700 Fps and nearly square for muzzle ME 2716 . Velocity at 500 yd. is 1770-1840 Fps and energy is around 1120-1210 Ft lb. . I'm sure I don't have to clue you on drop .

I put together a Dandy 1K+ yd. using a 22" Ballistics barrel Aero platform and it has not disappointed . Personally if I hunted with this Rifle ,I'd limit MYself to 550 Yd. for ethical Kills . Based on cartridge characteristics Not Rifle's abilities . Large Bull Elk or Moose ,I'd stay within 400 Yd. using a Quality 168 Gr. expanding bullet Nosler ,Berger ,Barnes or something similar . BOL .
 

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#37
The Armalites at PSA are smoking deals. Every Armalite large frame I’ve been around shot really good and has had tight reciever fit. I’d go 18” rifle gas over 16” mid.

The barrels Tony referenced are nice. I have 2 16” rifle gas, melonite, Criterion barrels. One 308 and one 6.5Creedmoor. Both shoot MOA or under 5 round groups with ammo they like. I’ve found no need to mess with adjustable gas blocks with either using a Surefire Socom Mini 2.

Skip the SMK’s for killing critters. ELD-M’s and Amax bullets work great.

I really like short large frames but lately I’ve been spending more time shooting my Grendels. An 18” Grendel ends up the same length as a 16” large frame and is easier to shoot. When you get the large frames off bipods or bags you’re going to have to work a lot harder to maintain sight picture, spot a miss, or follow up with a second or third shot.
 
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