I believe the XTP was designed for handgun velocities, and the XTP Mag is simply a heavier jacket for thehigher velocity muzzleloaders.
Only shot 2 deer with XTPs, one was with a plain XTP handgun bulletthrough the lungs broadsideand it went about 30 yards with a huge exit wound. The other was this winter with an XTP Mag and the deer was quartering toward me. I put it in front of thefront leg andthrough the body cavity toward the rear leg on the off side. No exit - bang flop - lungs looked like jello.
Both were 300 grain bullets, andpushed by 100 gr Pyrodex.