On the other hand, I've used Blue Dot in several cartridges, and had no problem. Same with Red Dot and Green Dot. Go figure .I wouldn't use Blue Dot with lead.
As for lead bullets, you just match hardness to pressure and your fine. I've loaded up to 1333fps in .44Mag with a BHN15 240g SWC with no problem. All I shoot is lead, and it isn't something to be afraid of. Just have to realize you can't shoot hard bullets slowly, and soft bullets fast. Never have used any gas checks either. Yes, throats have to be right, forcing cone, cylinder/barrel alignment, and no or just minor constrictions in the barrel.