RE: thompson omega piece of *%$#@??????
The comment about the primers is probably part of the problem. I have shot some pretty good groups with 209 primers but with Pyrodex. I am now using the .25ACP conversion that uses rifle primers and I get very good groups with fairly stout loads 82gr. of Black Mag3 runs 1980 to 1990fps. with the 295 Powerbelt out of my Omega.