I have had my Glock 22 since 1992 and it has only jammed on me one time. About 2 years ago while qualifying and it was my fault.
I had a wind breaker on and during one hand tatical shooting section of the course I got my gun too close to my body. The wind breaker caught up on the slide and did not let it close fully. I 'reacted' yanked the gun up to my chest (tore a hole in my wind breaker) TAPPED the bottom of the magizine, RACKED the slide back, and FIRED. Still got off all my shots.
This is the only time my G22 has jammed on me. Just a testament to how reliable they are.
I also have had a G17 since 1996 and it also has jammed on me, once. Again it was my fault. About 2am one night I heard my dogs outside my bedroom window fighting something I grabbed my flashlight, and my G17, (G22 is in my office in the duty holster) I went outside and there was an armadillo having a bad time with my dogs. Well this stupid armadillo is running right to me as my feet step off my back deck. I had time to shoot with my pistol upside down in my right hand pointing about 3/4's the way behind me. I felt the 'limp wrist' and that caused the failure to feed.
Anyway just had to brag about my Glocks.
ps G27 has not jammed yet........... it's waiting for me to buger up something I guess.