Bought 2 4X12X40 VariXll and put them on my Kimbers in 257 Roberts. Sigted the first in and it dialed in perfectly. The second, I adjust, but it wont move for 3-5 shots, then it seems to jump over, as my shots will then go where they are supposed to. Every little adjustment is like that. Took almost 40 rounds to sight it in, while the other took less than 10. Its not the gun, as shots are touching. Anyone have issues like that? I even tap the turret gently with some wood, but it doesn't seem to make a difference.