shell condition is definitely a big "if" there, the shells are inconsistently packed and apparently factory workers will steal the (hard) copper forcing wire that cleans the barrel from fouling from some of the shells... and powder that is not stored consistently is itself dangerous and unpredictable. heat, humidity, time, etc all can paradoxically increase the burn rate of powder grains, stabilizing agents leak out etc.

https://en.wikipedia.org/wiki/1967_USS_Forrestal_fire

there's an insane amount of 8mm mauser out there due to it being a relevant caliber for like 60+ years, and some of it has been stored in awful conditions and tends to... develop overpressure.

https://www.youtube.com/watch?v=AunvMjcJPHY

Aren't NK shells notoriously unreliable and have large rates of duds?