Originally Posted by robocop10mm
The live round in the chamber would have been put there by the slide stripping it of the top of the magazine. That round would have prevented the next round from coming up enough to strip off the top of the magazine. It would require something REALLY weird like the first round escaping the magazine during the rearward travel of the slide, a really defective magazine or some sort of shooter inducement.
You hit it--REALLY WEIRD. Took me a while to figure it out. Only happened
with an extended magazine. Glock 17, lightened slide, barrel holes and
compensator, shooting Major power factor ammo.
The Glock has a little ramp on the bottom of the slide that pushes the whole
stack of ammo down a bit as it comes back. For a nano-second, the ammo
column in the magazine is LOOSE--until the spring/follower reverse direction
and push everything back up against the feed lips.
If during that nano-second, the slide whacks back to full rearward travel,
it actually slaps the gun back a bit, popping the top loose round in the magazine out of the mag and into the chamber.
By the time the slide gets going the other way, the spring/follower has
pushed the ammo column up far enough for the slide to pick up a fresh
Loaded round in the chamber---slide trying to push another one in behind it.
Goofy but true. When the gun would start doing it, I would stretch the mag spring just a bit---problem solved.