I know this has been done before. But I've been wanting to cut down a Lee 515 450 mold for bullets to use in my .50-45 rolling block carbine. I have a Rapine 350 and a Lyman 515139 mold and they work well. But not being one to leave well enough alone, I decided to give it a try. The Lee molds were cheap, so I ordered two. Its always good to have a spare
I machined .175" off the base (one band and one lube groove). I had to shorten the sprue plate screw a little, but no other work was needed. Here is the machined mold next to the unmodified mold.
It drops the weight down from 450 to around 350gr. I think it will make a good option for my .50-45 carbine. It may also work well in my M1871 Springfield Spencer rifle that takes the same cartridge.