Tjcnole,

The primer misfires are caused by the primer carrier being crushed. If you look at the primer carrier, you will notice it is deformed and squashed relative to a new carrier. A primer carrier will last inversely to the amount of powder you use, really, by the amount of pressure your load develops. The blow back compresses the carrier, squashing it.

Noticed that you started with 150 grains powder. That explains why you didn't get much use out of that first primer carrier. 150 grainsin a new, rough bore, is a high pressure situation. Glad you were using light bullets with that. Do be careful.

Phil