Ditto, but mine is Fosbery choked.

I fired 600 rounds in almost 50 combinations - bullet/wad/powder/case/other changes. I had quite a few that grouped well at 50, then would not hit the target at 100. The bullets were destabilizing between 50 & 100 and flying all over the place. The only thing that kept me going was the belief that it must have worked when they sold the gun. Then magically, I stumbled upon a load that worked. When you find the load that works, it produces the 12 ga version of a clover leaf at 50 and 4"x6" or smaller rectangle at 100.