KCI has made good 15-round M1 carbine mags for many years.
Based on their carbine mags, I bought a couple of Glock 17 mags over a decade ago. One mag worked fine and the other was balky. My son is a Glock Advanced Armorer and he said the mags were constructed just like Glock mags. He also identified the problem with the balky mag as the follower catching on polymer overflash in the inside of the aluminum mag shell. He cleaned out the overflash and the mag subsequently worked fine.
A few years ago, KCI-USA was set up as a US distribution subsidiary and KCI reportedly improved quality control, so I bought a half dozen of the new gen2 mags. Five of the mags were fine; one mag had a little overflash and KCI immediately replaced that mag. Otherwise, I have had no problems with the KCI magazines.