well, in September i could pop a bottle at 200 yrds with my .17. now i take it out and it's surfing around the 100yrd target. couldn't have been the mount but i reset it anyway(loctite), checked the rings. took it out same thing happened after 2 nicely touching rounds then did an oblong circle of impact points. aside from cleaning i never took anything apart. it wears a BSA Sweet .17 3-12x40 which i blame right now.