Just a couple of thoughts on this. I have 1 load that sometimes doesn't cycle the action all the way on my PA10. It just happens to be a load my bolt gun loves. If you are using just 1 type of ammo try switching to a different round. Before doing all the work on the mag catch why don't you try modifying 1 magazine. Add some jb weld etc to the top of the notch and remove a bit from the bottom of the area so it moves the mag up some. If this solves the problem then look at modifying the mag catch and the work on the lower that that would entail. A lot easier to modify the 1 mag to see if moving the mags up solve the problem. Just a thought.