How to accidentally discharge your firearm properly.

[jdege]

The safety rules are additive. Follow all of them.

[daleamn]

Thanks for posting.
It would be interesting to know what gun he was using and if he had done any work on the gun.

[bofe954]

Oddly, when he drops his slide after unloading, his hammer doesn't follow, and he needs to pull the trigger.

[Sorcerer]

I would suspect dirty firing pin channel hanging up the firing pin. Or a badly seated primer.