I currently shoot a Burris 2-7 without posi lock. It is mounted on a Ruger SBH hunter in .45 Colt. within the first hundred rounds of cowboy loads (hadn't even started on the hot stuff) the cross hairs tilted(im assuming that the objective lense became loose and un-threaded some?) After I concluded that it was not my scope mounting skills, I sent it in and got it back within a week. It has since taken a lickin, and kept on tickin with lots of hot colt rounds. The customer service was great, and I don't have any concerns now, but I must say I was a bit disappointed in a brand new scope acting like that.