Let's play a game (from 1963) #2 w/answer

[Bocephus123]

Looks like even with a " pretty slim chance" I was right.

No sorry. bolt passed headspace from factory!

 

[Bocephus123]

Semi auto
Cartridge in chamber
Bolt closes
Bang, but no finger on trigger and no mark from firing pin.

Assuming the account is accurate, we can rule out the firing group (firing pin, hammer or striker, disconnect, sear and trigger)

Priming compound in the rim is set off from percussion or heat.

Option 1 - percussion - could be an improperly cut chamber allowing part of most of the rim to be crushed by the bolt face.

Some 22 autos were made with a very small bolt face (approximately the size of the rim). If the face were not square to the chamber and a bit long it cold slam fire by crushing part of the rim.

Debris on the chamber side of the shell rim or at the edge of the chamber acting like a firing pin and crushing a small area of the rim when the bolt closed. The mark would be on the wrong side and not confused with a mark from a firing pin.

Debris on the bolt fact acting like a firing pin -
inconsistent with description of no mark from firing pin.

Stuck extractor acts as a firing pin - Inconsistent with description of no mark from firing pin

Option 2 - heat, This is a bit of a stretch given the facts presented and no description of a heat source.

Defective ammo should be on the list, but not near the top.

answer is up read it now.

 

[Bocephus123]

No miss cut. no dirt debris. just one on one end of the spectrum. the other on the other end of the spectrum. both passed inspection!!! just a very rare slam fire! sorry i dont word well!

 

[Bocephus123]

I can see where both of the previous posts could cause the gun to fire.
I'm thinking chamber still has oil and not allowing cartridge to fully seat allowing the bolt face to hammer the rim of the cartridge.

this could actually happen

 

[Bocephus123]

Next!

 

[Catt57]

Next!

Already posted over here.

https://www.okshooters.com/threads/lets-play-a-game-from-1963-3.344700/

 

[Bocephus123]

is half cocked really safety

 

[Profreedomokie]

No sorry. bolt passed headspace from factory!

How do you know? Do you work there?

 

[Profreedomokie]

this could actually happen

 

[Catt57]

I think that any answer that said it was something to do with headspace and rim thickness was correct in spirit.