My BCs bore is .456" groove diameter, I don't remember the bore diameter, but I use almost exclusively range scrap, which while harder than pure lead, is just barely harder and I can still scratch it with a fingernail. My Lee 450gr FNPB casts at .461", and I lube with LLA and drive them about 1350-1400fps, which is enough for anything I need with this gun, but have driven them to a bit over 2K fps (won't give the load but the powder was 3031, and no pressure signs whatsoever) and no leading, so I wouldn't eliminate the "soft" alloys without giving them a chance first.