03-15-2022, 08:43 PM
Bill A. went with 1/7.5 twist for the short barrels, 1/8.75 on some of the premium rifles with 20 and longer, and 1/9 on the Shilen 20-24 barrels.
My 16 AA was 1/7.5.
You can run 1/9 through a stability calculator and it will show that its marginally stable/not optimized BC at 2350fps. It loses about 7% of the BC but will still shoot.
Change it to 1/8 twist at the same speed and it is optimized for BC.
My 16 AA was 1/7.5.
You can run 1/9 through a stability calculator and it will show that its marginally stable/not optimized BC at 2350fps. It loses about 7% of the BC but will still shoot.
Change it to 1/8 twist at the same speed and it is optimized for BC.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com