With a .452 bore, if you can find 453 or 454 diameter bullets, try them. If all you can find is 452, there's still some tricks. You do have a chronograph, right ? Are you casting these bullets? If it's a relatively soft alloy, say 11-12 BHN, I would use the non-GC bullet and start with the Titegroup powder. I wouldn't go over 6 grains or so. Maybe 1200 fps. Probably a tumble lube will work at that velocity, 2 coats. With the Lilgun, I would use the checked bullet, but that's just me. Use a good soft lube, 50/50 beeswax/Alox is a good one. Any of Lars' soft lubes from LS Stuff are good.