I chambered a Bartlein 1:7.5 twist barrel in 6 Dasher a couple years ago and used it off and on in PRS and belly matches. Finished barrel was 28 inches long. I had put about 1,500 rounds through the barrel and it still shot under .5 MOA on the regular.
I had used a fairly hot load initially in the barrel for about 1,000 rounds. Something like 32.5 grains of Varget with a 105 Hybrid. This load was hard on brass and barrels so eventually I switched to 31.0 grains and left it there for about 500 more rounds. The 31.0 grain load was initially at 2,900 FPS but it had dropped down to 2,860 FPS recently. Still shot very consistent and I won a couple very difficult/competitive belly matches with it at this velocity. Shot over 90% hits with it at the Sporting Rifle Match in Raton 2 consecutive matches and chronographed velocity many times.
I had some spare time this last weekend so I decided to chop off the tennon, re-thread, and re-chamber the barrel. I used the same reamer as initial chambering. The total tennon chop took off .75 inches of barrel. The muzzle end wasn't touched so the total length is now 27.25 inches. I bore scoped it afterwards and everything looks great. Nice even land cuts in the throat and the worst fire cracking was cut out.
I screwed it back on the same gun (Bighorn TL3) with the same suppressor and same muzzle brake mount. I went to shoot it and was hitting way high at distance after setting zero. I pulled out the magneto speed v3 and I am now running at 2,985 FPS average. Single digit SD and precision is very good so no funky stuff going on except my velocity is up about 125 FPS! 2,985 FPS also lined up perfectly at 1,000 yards for drop.
I would never have expected this velocity gain and I can't come up with a logical explanation for it. I have done the same thing to Dasher barrels before and only saw about a 30 FPS gain in velocity. I assume that is just from the throat being back to normal freebore again and the bullets having the shorter jump. Nothing with my loads changed. Still using the same brass, powder, and bullets. The same loads still shoot the same speed in my other Dasher barrels as before.
Any thoughts on how I gained so much velocity by shortening the barrel?
I had used a fairly hot load initially in the barrel for about 1,000 rounds. Something like 32.5 grains of Varget with a 105 Hybrid. This load was hard on brass and barrels so eventually I switched to 31.0 grains and left it there for about 500 more rounds. The 31.0 grain load was initially at 2,900 FPS but it had dropped down to 2,860 FPS recently. Still shot very consistent and I won a couple very difficult/competitive belly matches with it at this velocity. Shot over 90% hits with it at the Sporting Rifle Match in Raton 2 consecutive matches and chronographed velocity many times.
I had some spare time this last weekend so I decided to chop off the tennon, re-thread, and re-chamber the barrel. I used the same reamer as initial chambering. The total tennon chop took off .75 inches of barrel. The muzzle end wasn't touched so the total length is now 27.25 inches. I bore scoped it afterwards and everything looks great. Nice even land cuts in the throat and the worst fire cracking was cut out.
I screwed it back on the same gun (Bighorn TL3) with the same suppressor and same muzzle brake mount. I went to shoot it and was hitting way high at distance after setting zero. I pulled out the magneto speed v3 and I am now running at 2,985 FPS average. Single digit SD and precision is very good so no funky stuff going on except my velocity is up about 125 FPS! 2,985 FPS also lined up perfectly at 1,000 yards for drop.
I would never have expected this velocity gain and I can't come up with a logical explanation for it. I have done the same thing to Dasher barrels before and only saw about a 30 FPS gain in velocity. I assume that is just from the throat being back to normal freebore again and the bullets having the shorter jump. Nothing with my loads changed. Still using the same brass, powder, and bullets. The same loads still shoot the same speed in my other Dasher barrels as before.
Any thoughts on how I gained so much velocity by shortening the barrel?
