Get some pictures like Rockvapor suggested...that off center striking almost makes me think someone may have took material off the bottom of the bolt, enlarged the pin hole in the bolt, a bolt face issue or it isn't fully going into battery at times, but enough to fire, or the Bolt Carrier rails are badly worn.
Maybe Murray will see the post and have some ideas as to what is causing it. (and get you a new firing pin) If your strikes were closer to center I would blame the ammo...but there looks like something else causing it. The Murray pin alone couldn't be the cause of both popped primers and light strikes intermittently, in the same rifle during a session at the range. You would likely only have light strikes with Berdan primers, especially with a reduced power 27 Lb. spring.
Check to see that when you pull the bolt all the way back and let go that it slams forward and into battery several times in a row, to show the recoil spring is strong. Try to get some close-up pics of the bolt face and bottom, the Bolt carrier, inside the receiver, and of the Chamber and it may be apparent.