What even causes this

[u/Diligent_Studio6763]

Firing CCI Mini Mag out of a TM22. This was like the 4th round out of this 10 round magazine. I pulled the trigger it didn’t fire so I took the magazine out and this is what I saw. Went on to shoot another 100 ish rounds after this with no issues.

[u/BeerGunsMusicFood]

Turkey