The mechanical complexities of these things is mind boggling. I struggled to learn the time fuze of a No36 grenade! A couple of years ago a few of us had to mark a series of lessons given by potential instructors regarding their confidence to stand up and speak/talk/instruct in a natural way, so the actual subject didn't interest me. One bloke was 'instructing' us in grenades prior to a live outdoor lesson (where we threw a few). The complexity of the safety mechanism and fuzing was all too much for me but he was a very relaxed and laid back instructor who passed the course easily.
He was a REME Military Training (GD) Corporal and I spoke to him afterwards about his laid back approach. He said that it was because if we were a class of soldiers (instead of marking him.....) we'd all be very nervous or scared about the next lesson which was throwing the grenades. So he made it relaxed, interesting BUT very safety aware. Nice bloke too. Wrote to me afterwards about his new job!