scope problems on 7mm-08 encore pistol

[S & W 642]

I have a Encore 7mm-08 pistol 15 inch barrell and I was shooting the other day and my I noticed my scope was cooting back in the rings. I have a Bushnell trophy pistol scope and Leopold dual dovetail mount and Leopold Rings.  I Kept shooting and it wasn't changing my pattern and still shooting good groups. I checked the screws that hold it on and they were tight so I dont understand what was wrong.

[swampthing]

Sounds like you have a glossy finish on that scope. My leupold was doing that so I added another ring in the front and that solved the creeping., also a finger smear on the inside of the rings with some 3m adheasive will also keep things put. T'sob bases from SSK industries will allow up to 4 rings are also an excellent option.