My wife and I have three EZ's. Two are the standard model (no safeties) and one a Performance Center model. The two standard EZ's had to be returned for extraction/ejections problems. They are both fixed now and work well. The Performance Center EZ was returned because the gold grip safety...
My Franken-Performance EZ was returned today. It has the regular, black grip safety on it now, and is very pleasant to shoot. The gold grip safety that hurt my hand was returned also. Hope nobody else has the problem.
My first two EZ's both had to be adjusted as far to the right as possible to hit the POA. The third one, that I will get back from Smith tomorrow is a completely different story, and has earned its own thread, which I will publish after I shoot it.
Both of my EZ pistols have shot to the left, out of the box. They have been adjusted as far right as they will go, and it did the trick. Put blue Loctite on that adjustment screw.
I currently have two S&W 9mm semi-autos. One is an M&P 2.0, and the other a 639. One, I could skid down the driveway, all the way to the road, without feeling a twinge of guilt. The other, not a mote of dust would dare land upon.
Since the problem seems to be confined to the last round in a magazine, maybe the spring is not the culprit, but the follower, tilting or catching on something as the slide comes forward.