This reminds me of two stories of the PPsH.
The first was a hair raising tale of a German Sgt of the Waffen SS who had one of these. He recounted a tale of a patrol behind Soviet lines during the winter to find a lost Officer. Spent something like 6 days looking for him (successfully). It is way better if he was to tell it.
The other was during my 94/95 Yugo tour. I was a part of camp security. We had a..somewhat overzealous camp security officer who would, with one of the Senior NCOs, leave camp and then break into it through some random point, then send us to go fix it. This agravated the guards of the attached factory to no end as anyone who was breaking into our camp had already broken into their factory. That wasn't happening (they had a reputation of being a little trigger happy). The factory produced things like uniforms, ammunition, mortars and rifle grenades for the Bosnian army (or something like brake parts before the war).
One day, the CO of the Battle group went on a walk around camp with us (the shift commander and I) to see what is was we did (justify our existance). We went out to the guards hut, to tell them we were going for a walk through their compound to check the fence, would they like to come along? Well, we had a new face with us (actually, two, the CO and his interpreter) and it would be rude not to introduce them. Well, coffee happened and eventually things worked around to security. The guards were a little (drunk) upset that the Camp security officer had his little break into camp habit. they told the CO, in no uncertain terms that if they caught him trying to break into the camp from their side, they would take care of it (patting the 72-round snail drum on the PPsH they used for patrols). There was not another "security inspection" from the factory side of the camp.
I only ever heard them fire it once. It sounded much like ripping paper.
The guns I saw in Bosnia...