Right.. your Mag Hunter is an inline rifle. And your bore plug is a breech plug. As I kind of suspected.

That is not all that bad of shooting no matter which powder you choose. The Pyrodex group is very good actually with the one concentration of hits very tight. Fliers alway seem to happen. A little adjustment to the left and I think you will have a deer hunting machine there.

If you are shooting loose powder, try dropping the load down to 90 grains once.. just to see what happens. I have a CVA Staghorn Magnum that when loaded with 90 grains it is really accurate. With a number of different loads as well.

Good luck with your rifle.