Did you make any adjustments to the scope while shooting those 50 rounds? I would try and test the scope by making adjustments while shooting. I usually shoot a couple shots, adjust the scope up 8 clicks, shoot 2 shots, adjust to the left 8 clicks shoot 2 shots, adjust down 8 clicks 2 shots, then adjust right 8 clicks and the last shots should be close to your first 2. This should help determine if all is well with the scope's reticle (it will also help determine if your scope is canted). Sometimes there is slack in a cross hair due to turning the dial in one direction. Some longrange shooters (like Darrel Holland) recommend going past your desired setting a few clicks then comming back to it to take the slack out of the wire. If for some reason you had slack it may have come out, now that its been adjusted its OK.