Primer piercing-

What primers are you using for near max loads? There are some to avoid. Use thick cup primers such as Rem 7 1/2, CCI 450's.

Verify headspace and case sizing. This is critical.

Set firing pin protrusion to .035"-.045" not .060". Use light oil, NOT grease on pin otherwise light strikes and misfires can occur in colder weather.

Any bolt head work is a last resort.

Shouldn't be piercing primers without an ejector wipe and a heavy bolt lift.