# auto/semi-auto weapon behavior after squib-fire?

**URL:** <https://boards.straightdope.com/t/auto-semi-auto-weapon-behavior-after-squib-fire/668970>\
**Category:** Factual Questions\
**Created:** [September 16, 2013, 1:48pm UTC](https://boards.straightdope.com/t/auto-semi-auto-weapon-behavior-after-squib-fire/668970 "2013-09-16T13:48:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\
**Post date:** [September 16, 2013, 1:48pm UTC](https://boards.straightdope.com/t/auto-semi-auto-weapon-behavior-after-squib-fire/668970/1 "2013-09-16T13:48:22Z")

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Inspired by [this image,](http://i.imgur.com/k6V8xYQ.jpg) purportedly of a machine gun barrel after a [squib-load](http://en.wikipedia.org/wiki/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.

What else?

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<div class="post-metadata">

**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\
**Post date:** [September 16, 2013, 2:21pm UTC](https://boards.straightdope.com/t/auto-semi-auto-weapon-behavior-after-squib-fire/668970/2 "2013-09-16T14:21:55Z")

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Here are a couple of examples with an M-16 from youtube:

And one with a Tommy gun:
[![](https://img.youtube.com/vi/Nn4cgF_Sr3w/hqdefault.jpg "Tommy Gun Blow Up") ](https://www.youtube.com/watch?v=Nn4cgF_Sr3w)

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<div class="post-metadata">

**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\
**Post date:** [September 16, 2013, 3:14pm UTC](https://boards.straightdope.com/t/auto-semi-auto-weapon-behavior-after-squib-fire/668970/3 "2013-09-16T15:14:34Z")

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[quote=“engineer\_comp\_geek, post:2, topic:668970”]

Here are a couple of examples with an M-16 from youtube:

And one with a Tommy gun:

[/QUOTE]

The first and last videos show the barrel rupturing on the follow-up shot. The middle one isn’t so certain, though the caption does refer to the weapon exploding.

I’m more interested in how the weapon behaves when the barrel _doesn’t_ rupture.