870 slug gun problems
I have an 870 with a rifled slug barrel with cantilever scope mount, weaver steel rings and a Leupold VX-II 3-9x40 scope. I've been trying to get it zeroed in with no success. Once I get the slug hitting close (3 or 4 shots) then my next shots start hitting all over the place, sometimes 8 - 10 inches away. I rezero and get close and then the scope moves again. I've had this happen with several slugs. I have tightened everything on the scope and nothing is loose. I even filed some material off the forend to eliminate the forend/barrel contact I was having. Still, at some point zeroing in, my scope moves off by several inches and sometimes off the paper completely. Does anyone have any ideas or suggestions?