-We used the magazine as a monopod a bit. I've heard suggestions that could cause malfunctions in an MP5 type platform. Nope. Worked flawlessly.
-We also shot hollow points, which I had also heard MP5s don't like. the guy running the event is an instructor for the city's SWAT team and he's trained a lot with MP5s and thought it was poppycock but we tried it out anyhow. the only fatality was in the water jugs we were shooting
So, two "myths" busted for anyone keeping score