The MPH12 re not designed to hold the boat tailed TMZ properly causing gas to escape around the bottom. I have read that some guys place a number 16 washer at the bottom of their sabot and sit the TMZ on it. That keeps the sabot at the bottom tight against the bore when fired. I tried the TMZ in my Savage:
http://tinyurl.com/3vsc4a

But didn't try the 16 washer with an MMP12.My groups were good enough for hunting, but I wanted a more accurate bullet. This was last year whe I was just learning about shooting smokeless powder, which is what Blackhorn is very close to from a iginition POV.
Chap Gleason