[Unclenick]

Mdd,

Case capacity is critical to pressure and if varies from gun to gun even with the same brand because, at rifle pressures, it is the capacity the case expands to in the chamber that determines pressure, and not what it is as sized or new. So, your loads may or may not be reasonable in your gun? Please find an average weight fired case with the spent (and un-pierced) primer still in it. One of your 55 grain loads will be fine if they are the same cases. Weigh it empty, then fill it with water level with the mouth (no meniscus) and weigh it again. The difference in these two weights is the case water capacity in grains as fired in your particular chamber. Please let us know what it is?

Primer piercing has several possible causes. Can you post a close-up photo? Commonly it is not an actual piercing, but rather the primer cup has flowed back into the firing pin tunnel enough to blow out or has cratered enough to have a sharp enough bend to pierce. You can check not only the firing pin but the that there isn't excess space around the tunnel.

Also, basics: what rifle? What barrel length and twist?