30 cal barrel length question

[Boon20]

Im going to be building my first large frame ar soon as i can find parts. I am going with a 308 so i can use ammo for the gas gun as well as my bolt and im not to shure what barrel length im going to get. Im limited to 18" but i cant decide on 18" 20" or 22" with 1-10" twist. I will probably be shooting mostly 175g with occational 150g mixed in. So im wondering what am i loosing with an 18" or what am i gaining with 22"? I will be looking to shoot out to 1000y if posible

 

[Feesh]

I think it was TTAG that did a barrel chop velocity study. Depending on the round, it was between 15-25 FPS per inch of barrel.

An accurate match quality barrel at any length will deliver small groups, a little extra velocity may or may not help.

 

[sava]

I had the same issue when building my AR10. I decided to split the difference and go with a 20” Wilson Combat barrel and that seems to be the sweet spot as far as keeping the gun agile while still maintaining long range capabilities.

 

[Feesh]

TTAG Barrel Length and Velocty

 

[Boon20]

TTAG Barrel Length and Velocty

thanks i will look at this later tonight

 

[Boon20]

I had the same issue when building my AR10. I decided to split the difference and go with a 20” Wilson Combat barrel and that seems to be the sweet spot as far as keeping the gun agile while still maintaining long range capabilities.

I was leaning in that direction but could make up my mind

 

[Greg Langelius *]

I can't give you a logical basis why, but I find myself leaning toward the 18" length.

Call it Karma...

The only .308 I own and shoot is a 24" (bolt). It works well enough for me with IMI 7.62x51 168gr Semi-Auto Match.

Greg

 

[remington patriot]

For what its worth, I went with an 18" Proof Research stainless steel barrel and I am very happy with it.

 

[Boon20]

For what its worth, I went with an 18" Proof Research stainless steel barrel and I am very happy with it.

I was leaning towards 20" but as i was looking through other threads here i found that i would only be loosing 25 to 50ish fps so now im sold on the 18" barrels

 

[bfoosh006]

I love my 18" Criterion barreled .308 AR.

Far more nimble then the 20"

 

[RobbinsHGray]

My JP is 16” It is my favorite stick. Running Leupee MK6 with a BDC hitting steal off hand at 200 yards as fast as I can pull the trigger

 

[Boon20]

My JP is 16” It is my favorite stick. Running Leupee MK6 with a BDC hitting steal off hand at 200 yards as fast as I can pull the trigger

I cant have a 16" barrel im in canada and to keep it non restricted i have to have an 18 on a stag 10

 

[N-C]

If I have one AR10 308 for Multifunction ( target ; hunting ; fun shooting ; ~~~~~~ ) I will have 20”

But I do have 14.5” 16” and two 20” AR10 308

PS: I shot like 600 yards maybe 800 yards max

 

[N-C]

Results

308 Winchester Barrel length in inches versus Muzzle velocity in feet-per-second (ft/sec) Rifleshooter.com
Barrel length	Winchester 147 FMJ	IMI Samson 7.62 150 FMJ	Federal 168 Gold Medal	Winchester 180 PP
28	2965	2823	2706	2632
27	2962	2800	2697	2607
26	2955	2801	2673	2597
25	2917	2769	2659	2585
24	2909	2766	2635	2553
23	2877	2744	2618	2553
22	2837	2718	2597	2527
21	2807	2683	2580	2507
20	2804	2679	2565	2478
19	2757	2634	2532	2441
18	2739	2595	2523	2411
17	2707	2577	2481	2401
16.5	2682	2561	2466	2373
AVG velocity loss fps/inch	24.6	22.8	20.9	22.5

The data presented as a line chart

 

[N-C]

https://rifleshooter.com/2014/12/30...ato-barrel-length-versus-velocity-28-to-16-5/

 

[N-C]

308 bullet drop at 1000 yards

http://www.millettsights.com/resources/shooting-tips/ballistic-data-cards/

 

[aslrookie]

I chopped my 26” barrel down to 18.5”. No regrets. Still supersonic at 1000 shooting factory Federal 185gr juggernaut ammo and hitting a 10” plate at that distance.

FYI, this is on a bolt gun not AR10. I can’t imagine the results being much different other than a little slower with a gas gun and equivalent barrel lengths.