Am looking to load 420 gr. Cast in my 450 Marlin (calibre) BLR. I think the BLR will withstand more pressure than the Marlin Lever actions. Will be using 420 GC cast, was suggested to start at 48 gr. RL7, anybody got any further suggestions? Will be used strictly as bear defense at my cabin in the Chilcotin where the Griz are big! Thanks-Karl