Ruptured .22 Cases! DANG!

[lavgrunt]

I took my UMAREX MP-5 out to Burro on Sunday for a day of shootin' fun with a fellow 'calgunner.' First mag fired flawlessly! No issues! This is the 4th time it's been out snce I got it............

Second mag.......BANG! Lots of smoke, a little blow-back etc. Still had all my fingers and no blood on my cheek! Gun looks fine.......BUT WAIT!!! What's this on the bench?? Looks like an extractor and spring!! Yup.....a .22 round ruptured at the base and blew out the extractor assembly........all of it!! Everything else looked fine...........Oh well, back to UMAREX it goes !!!

My question is this; what causes a .22 case to rupture like that?? I did some searches and really got no definitive answer? Firing out of battery? Overcharged? What?

[Bartin]

what brand and type of ammo was it

[lavgrunt]

Remington high velocity........It's about 10 years old though

[50BMGBOB]

When That has happened to me it has been out of battery. Either the disconnect was a little off and let it fire without the case fully seated or in one gun, the rim was slam fired. Usually a really good cleaning with care taken to clean the chamber too and always check the disconnector too.