I sighted it in with irons for 50 yards with M193, So, I grabbed some of my leftover 55gr SP loads that I worked up for the old rifle. My POI shifted 2" up (not surprising) and 2" right (this was surprising). I admit that I am not great with irons, but this is consistent when switching back and forth 10 strings. ?
I have seen point of impact changes by changing ammunition, and I have seen point of impact changes due to position changes. It takes a lot of practice, probably years, with iron sights, to be consistent, and to be sure that point of impact changes are not due to positional changes. Your stock weld, where your face is in relationship to the charging handle, how you center the post in the rear aperture, where the rifle butt is in the shoulder, these all make a huge difference in terms of point of impact. Consistency with irons is a lot of work.
I took pictures of these two targets on the same relay at a Smallbore Regional. Each shooter is a NRA National Champion. When you can shoot consistent five round groups like this (twenty shots total for score), and the group moves when you change ammunition, then you can be pretty sure it was due to the ammunition, and not because of a shift in position or sight alignment.
When I shot M1a in competition, the stock weld was placing your cheek bone on your thumb. When the AR15 came in, you maintained a consistent stock weld by touching the charging handle with your nose. This was impossible in offhand, so you figured out a precise placement of the butt in your shoulder.
I can say, each and every time I lay down with my small bore prone rifle, the position is slightly different. And my zero's are consistently different between ranges, probably due to differences in the heights and slopes of the firing point in relation to the target. My zero's typically change a couple of quarter minute clicks, but they do change.
doesn’t look too shabby to me.
