If i'm right, the other two are spare barrel ports or something like that. And you're right, it is ridiculously complicated for a submachine gun. Especially an MP5. I'm not a fan. I mean...do you really need BOTH vertical foregrips on there? and seriously...who straps their tactical laser and light onto the silencer? A silencer which really doesn't look like it belongs on an MP5...or much of anything, for that matter. He did excellent modelling work, don't get me wrong. There are components that are cool by themselves, and he did a great job on the gun itself. I'm still not a big fan of the high-poly weapon modellers, though...but i guess that comes from my days of weapon modelling in the Half-Life engine.