The Gun Counter

A question that popped into my mind (not that it had to make a lot of room for itself...) watching some WWII documentary this week..

During WWII, was the 9mm ammo used in German subguns (MP-40 etc.) the same as used in their sidearms?

For instance, if you were a British Airborne type with a Browning, could you use ammo from a battlefield pick up MP-40 mag with no issues? Or was the subgun ammo significantly hotter than pistol ammo and risking Bad Things happening at Embarrassing Moments? (Such as what happened when SEALS used their extra hot MP-5 ammo in their Beretta's in the late 80's)

Or, even if the ammo is hotter, not enough to be significant over the likely amount of engagements.

For that matter, how about the ammo used in STENs and Stirlings?

I don't know. I've heard mention of hotter subgun ammo, but that may have been in relation to that 80s thing you mentioned.

Not sure about WWII but I saw some German sub gun Ammo kicked off a Steel Challenge match when it started bouncing back over everyone's heads...