Redding 3 die deluxe,7x57 AI, don't vibrate every reload but clean necks with rag every other, Use Redding graphite neck sizing media & lube gets inside.
jdk, it is possible the 2nd set was made at the same time as the 1st set & does have the same problem as the 1st. Redding said 1st had some chattering inside.
I may know if I have solved problem, will install a new RCBS RC tomorrow & give it a try. Should be able to tell something.