Outside of a worn out mag spring never any issues. They are almost boringly reliable...it's what they are known for besides having invented the chicken sandwich...oops ... wrong GA company...
I carried a Gen2, 22 for work and a Gen 2, 23 off duty for years. I shot thousands of rounds through both to practice and qualify, never had one problem. I carry a Gen4 26 now and have a Gen3 17 for home and range. I use my guns regularly and maintain them by cleaning and not over lubricating them. Some of the problems people have is soaking their guns in oil and wondering why they have problems. They seem to think if a little oil is good, a lot of oil should be better.......I also have a S&W 6904 that has been as tough as a rock. I still carry it on occasion because it is reliable, but I like my 26 with no manual safety. I have all of my 26 magazines with a plus 2 extension.
I have a G17, G19, G22, G34, love em' all. Only problem I ever had was when I put an after market trigger from Vanek Customs in my G34. Slide was locking back with 1 or 2 rounds left in the mag. Sent it back to Charlie and he tuned it a bit, never a probelm since. He's got that bad boy down around 2 lbs. There are definetly nicer guns, more reliable though ...I dont think so.
I've carried my Glock 33 almost everyday for going on 8 years. Shoot thousands of rounds through it at the range over the years. I've never had a single issue with it. With night sights and the clip draw, its my favorite gun to carry.
Most definitely..buried an old G22 in mud and dirt and water, picked it up and fired away. And being that my guns will never see that much abuse again, I see them being 110% reliable.
My model 21 has been a damn good gun. I like the way it shoots, always been accurate, but it doesn't take well to every type of ammo. GA Arms has been 100% reliable through it, Gold Dots and Black Talons have been 100% as well. However, I have had a little FTE trouble with the blue box range ammo and the aluminum cased stuff I gave away before I finished.
It was the first pistol I bought at 21 years old and when I did, all I caught was crap. "Does that thing say matel on the side?" "I wouldn't have that plastic POS." Just about every old timer around made fun of it. Now it seems that same crowd has switched to Glocks. I find them to be high quality weapons, above and beyond everything else, no, but right there by some of the others at the top.