Inspired by this image, purportedly of a machine gun barrel after a squib-load (and half a dozen rounds fired in behind it). It’s not clear whether the weapon finally stopped working, or the operator noticed something was wrong and released the trigger.
Question: how does an automatic or semiautomatic weapon behave when firing the rounds after the squib-load? Presumably there’s no recoil, since the obstructed barrel stops each bullet immediately after it gets fired. Presumably there’s also a massive blast of gas each time the slide comes back to eject the brass, since all of the propellant gas must now exit via the breech.
I get that the barrel can rupture under some circumstances, although it appears not to have done so in the above-linked image.