[Smokey Joe]

Blancoman--A "regular" neck sizing die will first squeeze the case neck down a bit too far, then size it right by pulling a sizing button up through it. Nothing wrong with that as far as getting the sizing right, and it's been done for many years.

A Lee Collet die will just squeeze the case neck to the correct size in the first place, by squeezing the neck between a precisely sized mandrel on the inside, and the collet on the outside. Lee claims that this will result in more accurate ammunition--Don't know about the comparison, but the Collet Die DOES make accurate ammo.

The real advantage as I see it is that the Collet Die only works the brass of the neck once in resizing, compared to working the brass twice with the other type of die. Working brass tends over time to make it brittle, resulting eventually in split case necks, so the fewer times a piece of brass is worked, the longer it lasts.

I believe that Lee owns patents on the collet neck-sizing die, so, no, yr RCBS dies won't be of that type.

I have Lee Collet Dies for neck sizing, in several cartridges, and am very happy with the results obtained from them. However, were I you, I would NOT rush right out and replace all my "regular" neck sizing dies with Lee Collet neck-sizing dies. I would, however, try a LCNSD the next time I was setting myself up with dies for a new cartridge.