Hi ya, Frogg!
I used to do almost all my .30 Carbine shooting with cast bullets. I dunno about your bullet mold, but the ones I've used were the Lyman RN and Lee RN in about 110-120 grain weights. Linotype metal is preferred, but I mostly used wheel weights tuffened up with tin added to the melt. I almost always got better accuracy with the lead bullets versus factory .308" jacketed bullets.
They work just fine, and when used with gas checks you can push them right up to jacketed bullet velocity and accuracy. I've fired tens of thousands of these bullets using H110, WW 296, Hercules 2400, and even Herco powders. Try to load for reliable functioning and accuracy, and not strictly for top velocity.
Please be advised, that the American Rifleman technical advisor predicted that after a couple thousand rounds, the gas regulator plug would need to be removed and the gas port hole cleaned out with a twist drill. That proved true, because lead and fouling material tends to plug up the gas port. Routine cleaning is needed to keep the Carbine reliable. it's not hard to do, and is a small price for shooting cheap bullets and ammo.
