I've noticed something about some subsonic loads. You expect the bullet to have a lower point of impact at any distance due to the lower velocity, but some very consistently hit a bit to the right. The one I tried recently grouped very tightly at 50 yards, but an inch to the right. That was in .308, a while back I tried some subsonic loads, both factory and reloads, in 7.62x39 that hit a bit more to the right as well as lower.
I'm wondering if it's the difference in recoil in those loads, or something else. Any thoughts?
Added:
This is on an indoor range at 30 yards, from a rest, so no wind. The .308 was tried at 50 outdoors, but not wind there either.
All cases trimmed, and bullets seated to the same depth. That's a slightly different depth than the full loads, but consistent.
I spoke with a guy I know who's an engineer who has studied lots of things, he says it's the weight combined with different time in the bore due to lower velocity causing the bullet to leave the muzzle at a different time than the full-power loads.
All cases trimmed, and bullets seated to the same depth. That's a slightly different depth than the full loads, but consistent.
I spoke with a guy I know who's an engineer who has studied lots of things, he says it's the weight combined with different time in the bore due to lower velocity causing the bullet to leave the muzzle at a different time than the full-power loads.
It may be that the bullet is engaging the rifling at a slight angle. 3 things to check: (1) Is the brass at the case mouth square and concentric? I trim my brass every time it's used. (2) Is the bullet seated perfectly straight? Have to use a dial indicator for this one also. (3) Is the crimp even all the way around? It sounds as if the issue is consistent as all shots group to the right. I usually check my reloads first and if that is good move on to my shooting skills.
ReplyDeleteSuspect interaction between gun, shoulder, and increased time in bore of the bullet. Try a lead sled or some other mechanical rest to rule out shooter. Do you use the same range, with similar cross wind? An inch at 50 is 2 MOA, which would take quite a breeze. Ammo problems would increase dispersion, not move group.
ReplyDeleteI have had this occur with factory loads in .300, and have always wondered the same thing
ReplyDelete