I believe a 3" group at 100 yards is standard MZ accuracy. I know some will jump in and say you should have 1 hole groups but that's with load development, quality bench rest and and plenty of skill.

I'd switch to loose powder. If it's T7, you need to swab between shots Try between 90-110 grains by volume with a 250 - 300 grain bullet. The groups and your confidence will improve.