Only two things I can think of would be:

1. Your barrel is a copper mine

2. Your rings were not pushed forward against the base when mounted. Just like picatinny stuff, Warne rings must be pushed forward against the slot to keep them from slipping under recoil.

X-VERMINATOR

Sooner or later our heritage of hunting is going to be a rich mans sport and the words "Outfitter" and "Hunt Industry" will be synonymous with cancer and A.I.D.S. among blue collar hunters like me and my family! (A.L. Williams - 2010)