Semi-auto shotgun bolt not locking back

[bigbearbear]

Wife and I went shooting at Coyote Valley today, when paying for our tab, I saw this customer bring to the counter a semi-auto shotgun (a rental I think) and complained about it not locking back.

One of the girls at the counter checked it out and I saw that she tried cocking back the bolt but it won't stay back.

Just out of curiosity, any idea what kind of malfunction that will cause something like this to happen? Although both wife and I shoot semi-autos, I've never really understood the locking back mechanism of our shotguns and that incident piped my interest. On my Benelli shotguns, with the gun being empty, if you cock the shotgun and squeeze the trigger, then cock it again, the bolt will catch. Alternatively, there's a bolt catch button you can press, then cock the bolt back and it'll catch the bolt too.

And no, I didn't ask them what shotgun it was because they were busy.

Thanks.

[grantar2]

When I first bought my ATI semi auto it did exactly this. Cause was a faulty trigger group. There was a lever on the side not properly aligned. ATI replace the complete trigger group.

[axhoaxho]

It could be many things, yet the first-suspect could be the carrier latch (please see below of a quick pic that I found from the web. )

Depends on the brand of shotgun, the carrier latch basically could be a spring-load latch that pivots in different positions to hold/release the bolt. And it usually is with a bolt release button for user to manipulate, so the user can press and release the bolt. Something like that, just to give an overly-simplified idea of how it works.

The case that OP saw could be due to dirt built-up behind the carrier latch, around the spring and pivot area that affect the latch movement (especially if it was a rental gun, which didn't get clean often.) Or it could be something broken in the carrier latch (bent latch, broken pivot, damaged spring, etc.)

If it were my shotgun, I would check the carrier latch first. And if it is not the problem, then I would move on to other areas (trigger group, etc.) for further troubleshooting.

Just my thought...

[bigbearbear]

Thanks guys, this is good to know.

[ducky_0811]

Many shotguns are designed to not lock back unless the trigger has been pulled or a separate button/lever has been pressed to release a shell from the magazine and the tube is empty. Could an unfamiliar operator.