Seat those primers until they hit the bottom of the pocket .
Ease up on the lever and spin the case 1/2 turn in the shell holder and press the primer in again to make sure it's fully seated and not cock-eyed .
This cured all my "light strikes" and "hard primers"...try it .

Little hand primers don't develop a lot of power like a press so you have to pay attention to how deep the primers are goin in.
Gary

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Certified Cajun
NRA Member