Re: RCBS vs Redding dies
For what it's worth, I found that if the sized case neck's straight, one can seat bullets very straight with a ball peen hammer or a conventional bullet seating die. No in-line "competition" seater I've tried does all that well with bent case necks. I've tried Wilson, RCBS, Vickerman, Bonanza and a couple other "in line" seaters, all with pretty much the same results. After seating bullets in even slightly bent case necks with these dies, they're still bent almost the same amount at the same place.
Expander balls are the biggest cause of bent case necks. Use a gelded die, such as the full length bushing dies made by Redding or RCBs with the bushing diameter about 2 to 3 thousandths smaller than a loaded round's neck diameter. They ain't got any balls so case necks are much straighter coming out of the sizing die.