As a die-hard Glock convert, I can honestly say, they'll jam, for sure.
I've experienced numerous malfunctions with my G-17, though to be honest, probably less than a dozen or so were when firing factory ammo, and mostly with Remington/UMC 115gr ball. Had the extractor slip a rim a few weeks ago, a stovepipe a few weeks before that and those are the ones I remember for certain. Had some with weak reloads, but I can't blame those on the pistol.
GF's brother, Marine, had a malfunction within the first 100 rounds out of his new G-23. Using Remington Golden Sabers no less.
Had a few malfunctions with former Glock 26 that I traced to an improperly assembled part (oops...
).
And of course, my dad and brother can get my 17 to malfunction somehow, but I don't know how they do it!
That's about all I can remember for now. They HAVE been mostly trouble free for me, and the 17 is my go-to pistol, even over my S&W revolver!
Edited: An I've seen loose-grip related malfunctions with this. A 1911 works OK for my gf, but my 9mm Glock won't feed at all. They definitely seem more prone to limp-wristing than steel-framed autos IMO.