And the Uzi went "Rat-tat-tat-tat-tat-tat, POP!" The bolt rode back half way and stopped in a cloud of smoke from the ejection port as the top cover bulged and snapped loose of the rear catch, flying open.
That's not supposed to happen.
Squib load while testing a new ammo recipe. That bullet lodged in the barrel just ahead of the chamber and the next round fired into it, immediately expanding and plugging the bore. With the barrel thus obstructed, all of that pressure had to go somewhere and it did--right back into the action.
Fortunately the Uzi is over-built like a little tank so this is fixable. I may or may not be able to salvage the top cover but I have spares and those are cheap. The bullets are already out of the barrel and it doesn't appear damaged, but I have spare barrels, too. The main thing is that the receiver is unharmed; that would have been cause for tears had it been damaged. But Uzis are tough and the gun will be ready for test-firing as soon as I get around to putting it back together. Still...quite the downer on the range, especially as it was only about a dozen rounds into the first magazine.
But it also stands as a good reminder to all though about why we wear safety glasses when we shoot. A lot up unburned powder and brass fragments came back out of that ejection port and that could have been nasty had it caught someone in the face. Precautions, folks!