Does the die have an expander rod (Lee) or a ball/bullet (RCBS and others?). If Lee, the recapping pin is the expander rod and is tapered, so you have to make it fully insert into case not barely touch the primer (you’ll get small ID if it doesn’t go all the way in). If it’s an expander ball, make sure it is right size as mentioned but then be sure it is pressing into case and popping back out when retracting, you should feel that on way in and out as pressure needed to move press handle changes.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!