Which of these two barrel lengths would be most advantageous for both competition shooting and hunting and why? Would a longer barrel be better? If so, why? Thanks in advance for your input!
18.5" .308 Barrel vs. 20"
- Thread starter wmfirefighter
- Start date
1.5 inches of barrel is splitting hairs. Performance wise, no meaningful difference. Only you can make this decision imo, it’s simply a personal choice.
The difference would be around 150 FPS maybe and would only matter if you wanted to wring out every FPS you could for long distance shooting. Here's an article about barrel length that may help you although this one is using a 6.5 creedmoor with the .308 further down the page.
Effect of barrel length on velocity
Effect of barrel length on velocity
That makes sense. What about with something like a 22" barrel? Is there a performance uptick with the 22" or maybe even a 24" barrel?
No way in hell 1.5” of barrel will lose him 150 fps. In my actual experience, I’d say more like 40-50.
The .308 does quite well out of a 20" barrel.
However, when you consider the velocities involved and the somewhat pedestrian BC's of the typical bullet weights suitable for the .308, longer is normally better.
24" is a really good length, if you aren't running a suppressor. Once you add the 9" of a can to that, it becomes a bit unwieldy.
I really like 24" on my .308, however, my primary .308 gun wears a 20" barrel because it was too damn long with the can on it.
If you are thinking of competing, go 24", if is is going to be a hunting gun, 20" will do.
I lost 25 fps when i chopped a .308 down to 18 from 22 inches. For me and that rifle it was worth it, I am still able to make hits at 1000 yards pretty reliably. I read on the forums that 25 fps is what i would lose and thats what happened.
If your going to build one I'd go 18" or under with a .298 bore over a std .300 bore an powder in the IMR3031 burn range. Out to 600yds my 16.5" .308 gets it done just fine. It's short, lite an swings fast. I shed all my .308 bolts that were longer an now am shedding the longer gas guns as well.
When I started as an LE Sniper almost 20 years ago, I had a factory rifle with a 26” barrel that shot Hornady 168 gr. AMAX TAP at 2700 fps. About ten years ago, I switched to a custom rifle with a 20” Hart barrel. It shot the same ammo, unsuppressed, at 2650 fps. I just switched to an AI AX308 with an 18” Bartlein barrel about three months ago. It shoots the same ammo, unsuppressed, at 2550 fps. The barrel length certainly has an effect, but some barrels are just faster than others.
I like the 18” length for its handling qualities in close quarters, whether suppressed or unsuppressed. If you’re hand loading for comps, you can tailor your load to the longer barrel lengths, such as 24 or 26 inches, and likely get a little more velocity for improved performance at longer ranges. However, if you’re shooting suppressed, or shooting comps where the longer barrel lengths would be a disadvantage, I’d stick with 20 to 22 inches as the best compromise between handling and velocity, with 20 inches being my favorite length for a general purpose 308.
I like the 18” length for its handling qualities in close quarters, whether suppressed or unsuppressed. If you’re hand loading for comps, you can tailor your load to the longer barrel lengths, such as 24 or 26 inches, and likely get a little more velocity for improved performance at longer ranges. However, if you’re shooting suppressed, or shooting comps where the longer barrel lengths would be a disadvantage, I’d stick with 20 to 22 inches as the best compromise between handling and velocity, with 20 inches being my favorite length for a general purpose 308.
GO WITH THE 18" IT'S A WIN WIN BUT WHAT WOULD I KNOW 
Mike R.
Tac Ops
Mike R.
Tac Ops
GO WITH THE 18" IT'S A WIN WIN BUT WHAT WOULD I KNOW
Mike R.
Tac Ops
You’ve been answered by 308-short-barreled royalty. You now have no option but to go for an 18inch barrel, sorry.
I’d do 18” if you’re hunting with it. It’s just so much nicer to maneuver. DARPA did extensive research on .308 barrel length while developing the XM-3 and settled on 18.5”. When I cut my factory AAC-SD down to 18” it was still capable out to 1000 yards and none of the animals seemed to notice a difference.
I have 16-24” 308s in every conceivable variation. 18” with a 1/8 twist and 175 SMK accurate load is only 150 FPS (8208 xbr) off the accurate load for the 24”. I like the 18” over the 16” because the weight of the barrel balances the rifle better. It naturally points easier. Plus, 18” and a suppressor is a usuable length.
Velocity loss and barrel length is very powder dependent. When I use Benchmark powder the velocity difference between the 24 and 16 accurate load is 60 FPS. Just my experience.
Velocity loss and barrel length is very powder dependent. When I use Benchmark powder the velocity difference between the 24 and 16 accurate load is 60 FPS. Just my experience.
My AT came with a 20” barrel. I have plans for 18” 6.5CM and 16.25” 10 twist .308 barrel for it.
But I have no interest in any barrel over 22” for any caliber.
I say go 18”.
But I have no interest in any barrel over 22” for any caliber.
I say go 18”.
Mine is 16.5" an I see no need for anything longer for what I do with a 308. If I need to go past 600 I'll move closer or drag out the 300wm.
Mike,GO WITH THE 18" IT'S A WIN WIN BUT WHAT WOULD I KNOW
Mike R.
Tac Ops
What would you recommend to LE on a .308 working gun (that's not me) running a 7" or 9" suppressor?
Still 18" or 16.5"?
You could go 16.5 if your LEO and you're running a can I've built tons of those...
I like18" on a LEO 308 because with Fed Match your getting around 2580 to 2620 and I've seen higher depending on the Chamber...
Mike R.
