[Jerry45]

The primer seating punches (large and small) for my 550B do not have any grooves in them. I seat them all the way (as far down as they will go) in the hole then tighten up the set screw. I’ve never had a problem with the plate dragging on a primer or the retaining cup.

Actually there usually isn’t a primer in the punch when the plate is advanced. You put a piece of brass in, drive the handle down, which seizes and decaps and picks up a new primer. Then you drive the handle up which drives the case out of the sizing die, give it an extra up stroke to seat the new primer. Then you advance the plate. There is no primer in the punch at that time. Now I’m not saying the plate won’t advance with a primer in the punch, mine will. However in actuality when you’re loading there normally isn’t a primer in the ram when advancing the shell plate.