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Re: 308 Barrel length
I believe most (maybe all) of the work done in the Houston warehouse was with the 6mm PPC for the 100 yard benchrest crowd, the optimum barrel length they came up is for that cartridge at that range. The paper written about the testing in the warehouse is interesting from a number of aspects but was focused at finding the best recipe for the shortrange BR crowd.
That does not mean that the barrel length they recommend would not work well for other applications. The barrels on my hunting rifles seem to get shorter as time goes by as the shots I take are inside of 400 yards, think lots of trees. But reaching 1,000 yards with the 308 at sea level with a short barreled (20" or less) rifle and say M118 LR or Blackhills 175 SMK, is a challenge as it will in most cases go subsonic before the target.
I did a lot of testing with the XM-3 a few years back with issued M118 LR (07 lots) and shooting just west of Camp Perry in OH the XM-3 would be transonic around 800 yards. If you handload and are willing to work the pressures up and/or use other bullets you can get 1,000 yards with an 18-inch barreled 308 but if you do not handload and are shooting at DA's less than maybe 2,000 feet you may want to consider longer barrels to reach 1,000 yards or use a 260.
The testing with the XM-3 was done for a DARPA contract and the PM would be shouting at us that he did not want to hear that the XM-3 could not reach 1,000 supersonic he just wanted us to fix the problem, but we could not use different ammo. Finally I said we could solve the problem lets just move the testing to 6,000 foot elevation or greater. So we went off to Hawaii to shoot on a Marine base up the hill on the big island.
I am currently building my FT/R competition gun for next Summer's F-class season for 1,000 yards will be sporting a 32-inch barrel to squeeze every last bit of speed out. My F-class gun will weight 18 pounds with scope and bipod and only carried from my car to the line so the 32 inches does not hurt me at all. The gun does not have to swing nice to acquire or track targets as the paper it don't move.
What is the optimum length? What is the intended use of the gun?
I believe most (maybe all) of the work done in the Houston warehouse was with the 6mm PPC for the 100 yard benchrest crowd, the optimum barrel length they came up is for that cartridge at that range. The paper written about the testing in the warehouse is interesting from a number of aspects but was focused at finding the best recipe for the shortrange BR crowd.
That does not mean that the barrel length they recommend would not work well for other applications. The barrels on my hunting rifles seem to get shorter as time goes by as the shots I take are inside of 400 yards, think lots of trees. But reaching 1,000 yards with the 308 at sea level with a short barreled (20" or less) rifle and say M118 LR or Blackhills 175 SMK, is a challenge as it will in most cases go subsonic before the target.
I did a lot of testing with the XM-3 a few years back with issued M118 LR (07 lots) and shooting just west of Camp Perry in OH the XM-3 would be transonic around 800 yards. If you handload and are willing to work the pressures up and/or use other bullets you can get 1,000 yards with an 18-inch barreled 308 but if you do not handload and are shooting at DA's less than maybe 2,000 feet you may want to consider longer barrels to reach 1,000 yards or use a 260.
The testing with the XM-3 was done for a DARPA contract and the PM would be shouting at us that he did not want to hear that the XM-3 could not reach 1,000 supersonic he just wanted us to fix the problem, but we could not use different ammo. Finally I said we could solve the problem lets just move the testing to 6,000 foot elevation or greater. So we went off to Hawaii to shoot on a Marine base up the hill on the big island.
I am currently building my FT/R competition gun for next Summer's F-class season for 1,000 yards will be sporting a 32-inch barrel to squeeze every last bit of speed out. My F-class gun will weight 18 pounds with scope and bipod and only carried from my car to the line so the 32 inches does not hurt me at all. The gun does not have to swing nice to acquire or track targets as the paper it don't move.
What is the optimum length? What is the intended use of the gun?
Re: 308 Barrel length
Took an 18" bolt gun, shooting Black Hills 175s out to the Accuracy First Course and had NO degradation in accuracy out to 1200-1300 yds (1100-1200m). Didn't have enough scope to engage the mile shot. Almost everyone else was on a 16" OBR shooting 175s with no issues at all past a grand.
Took an 18" bolt gun, shooting Black Hills 175s out to the Accuracy First Course and had NO degradation in accuracy out to 1200-1300 yds (1100-1200m). Didn't have enough scope to engage the mile shot. Almost everyone else was on a 16" OBR shooting 175s with no issues at all past a grand.
Re: 308 Barrel length
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: timelinex</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">If you study the "Secrets of the Huston Warehouse" and Dr Mann's
"The bullets flight from powder to target"
You see that the most accurate barrel would be 17 3/4" .
In a gas gun such as a M14/M1A I like to go to 22 inches because with their existing flash hiders you get no muzzle flash (detectable at night) using M118 and simular loads. </div></div>
Pretty sure it was 21 3/4 .....</div></div>
X2
It was either 21&1/2" or 3/4 it was proven to be the most accurate length for the .308
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: timelinex</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">If you study the "Secrets of the Huston Warehouse" and Dr Mann's
"The bullets flight from powder to target"
You see that the most accurate barrel would be 17 3/4" .
In a gas gun such as a M14/M1A I like to go to 22 inches because with their existing flash hiders you get no muzzle flash (detectable at night) using M118 and simular loads. </div></div>
Pretty sure it was 21 3/4 .....</div></div>
X2
It was either 21&1/2" or 3/4 it was proven to be the most accurate length for the .308
Re: 308 Barrel length
I think 18" is best all round for .308
I think 18" is best all round for .308
Re: 308 Barrel length
Back when the .308 was in the benchrest game (long long time ago) the barrels averaged 20-22 inches long. The guys shooting 1000 yards then and now tend to run barrels 28-32. The longer barrel gives needed speed at the long ranges. I made rifle barrels for a living (retired now). We typically used 1-12 on .308 up to 175 grain bullets. However, a 1-10 twist is the go to twist.
Back when the .308 was in the benchrest game (long long time ago) the barrels averaged 20-22 inches long. The guys shooting 1000 yards then and now tend to run barrels 28-32. The longer barrel gives needed speed at the long ranges. I made rifle barrels for a living (retired now). We typically used 1-12 on .308 up to 175 grain bullets. However, a 1-10 twist is the go to twist.
