 Prior to the arrival of the .458 Lott there were a few other .45 caliber (11.6 mm) cartridges with similar performance levels based on the full length .375 H&H Magnum case such as the .450 Ackley Magnum, .450 Barnes Supreme, .450 Mashburn Magnum and the .450 Watts Magnum.There are only minute variations between these cartridges.Most .458 Lott chambers will accept the .450 Watts cartridge as the chambers are reamed to accept a cartridge.