Strange
Hmmmmmmmmmmmmmmmmmm
Ken...How heavy is the recoil spring in that shooter? It almost sounds like short-cycle malfunctions. The tip is that it runs one day, and goes fugasi
the next.
Last-round malfunctions like yours are almost always a short cycle, a weak magazine spring, or an unstable follower that isn't consistent...and it'll show up on the top round or the last round 99.9% of the time.
Is there any indication of the slide getting into a bind when you hand-cycle it? Will the pistol lock the slide back on empty if you deliberately take a limp grip? Load one round and check it a few times.
How about the ammo? Good, consistent stuff that doesn't vary a lot in
recoil or report? Some of the bargain basement brands or commercial
reloads will do that in some lots. I won't name a particular brand, lest it bring howls of indignation...but I have seen it happen a lot. Does the brass always kick well clear of the port...or does some of it dribble out onto the ground?
Try a known good brand of ammo...Federal American Eagle is a good place to start. Stick with 230 grain for the present. One box should tell the tale. To check as many last round feeds as possible, load two rounds per magazine for the test.
If all else fails...you ain't that far away. Bring'er on up here and we'll have a look-see. Coffee and tweakin' is on the house.