(1) Lol you obviously have never used the m5k. (2) It's got a clip of 21 bullets. It fires the entire clip in a second and most of them need to hit a target to get the kill. (3) It also makes it easier to switch from 1 target to another without having to reload as much. Holographic is self-explanatory since the iron sights on the thing suck as much as the standard mag.
(1) I haven't
idk if I've even unlocked it yet
I don't use the MP7 usually though, it fires way too fast for comfort, and I'm not a huge fan of close-range either
but I do use a UMP for my support class, because I mostly hate all the LMGs and the other PDWs I have suck even worse
(2) that's a reason I don't like them
(3) well, I have (what may be) a bad habit of reloading after every kill, so I wouldn't notice anyway
it's gotten me killed a few times :x
sorry for being as hostile as I was btw. didn't mean anything by it