The heavy for caliber hollowpoints are very useful out of pistol caliber carbines. The longer tube allows fair velocities, well over what a typical handgun could generate. Launch one of those heavy .44's out of a carbine with enough twist to stabilize it, and you have a rig that hits hard.
Another arena are the long barreled single shots like the T/C', with 10-14" tubes they can likely drive the heavies hard as well.
Finally, at least some of those heavies were likely intended for the .444 Marlin, which recieved a real boost in usefulness to its fans when it received slugs in the 265 and up range.