The ones for 45-70 are the rounded tip, to work in tubular magazines. So, that's not the same as the ML bullet, although you can certainly use them as such. I don't know if the SOCOM bullet is the same as the ML bullet.
You can shoot any .458 you want in a single shot or falling block 45-70. The Speer 350 grain Hot-Cor shoots ragged holes from my Scout V2. Tubular magazines require the appropriate round or flat point bullets to ensure primer detonation doesn’t occur due to recoil in the tube.