Not sure if they already added this, someone already made a thread about this bout whatever. I feel like they should make like more attachments for more guns not just the M4, also it'd be nice to have an extended clip also, and maybe like a supressor for looks?  

This has been suggested many times in the past.

Really, this sort of thing would be solely cosmetic for guns.

Also there's no reload time so an extended clip doesn't quite fit in.