The belt is needed on an H&H case because of the gentle (long)shoulder angle. It isn't sufficiently steep enough to headspace on.

On a straight wall case such as the 458 Lott there is no shoulder so the belt provides the "shoulder" for correct headspace.

On a bottle necked cartridge like the 300 Winchester magnum there is a shoulder to headspace on. But the cartridge headspaces on the belt. But only until that case has been fired and formed to the chamber dimensions. So in cases like these the belt is not needed and only redundant.



The 300RUM can be had in a Remington SPS which retails for$530 new.