Originally Posted by sabotloader

Muley - then you are back to the 300 grain Thors for the MR. It will shoot them just fine even with the bore problem at the powder end. The bullet will obturate to the bore both up and down.

The only thing might be if you can hold compression of the bh long enough to get total ignition. If not you might have to go to T7 which is not all that bad.