http://magsafeonline.com/prices_specs.php WOW! I am not associated with MagSafe in any way. Nor do I agree with the concept of a defensive bullet that fragments at impact. But this sort of shoots down the idea that you “cant” get MachII speeds from a duty pistol. Obviously, it can be done. The issue, really, is caliber and bullet weight. Given the .460 Rowland and a solid aluminum HP, with a large conical base cavity (ala THV Arcane) you are talking about 60 grs at 2400 fps from a 4" barrel.
That will be the same recoil/momentum as 120 grs at 1200fps, but it will be 760 ft lbs. If that same hp is slit from the nose to near the base, it will break into 2 large fragments at impact. Those segments will tumble in the target, tearing up a lot of tissue and transmitting a lot of shock. They will diverge from each other, too, creating 2 separate wound channels.