I have had excellent results with the SPEER 300 as well as the SIERRA 300, both SP. The canelure on the SIERRA makes it too long for lever-action functionality... but its just fine in a Handi!!
I do have the 300XTP Mag bullets, but haven't shot any game with them... Sorry I don't have stead fast info for you on the MAG XTP bullet. But I can attest to the performance of the first two bullets I mentioned. They perform as well at the higher velocities attainable from a rifle barrel.
CW