Designed for the "Genosian Rebel" request.
Monkeyman; this is a 'carbine'?
A carbine is a firearm similar to, but generally shorter and less powerful than, a rifle or musket of a given period. There have been many carbines developed from rifles, being essentially shorter rifles firing the same ammunition, although usually at a lower velocity.
This looks like a pretty long rifle!
If you took off that top extension of the barrel it would be a carbine, but then it would look exactly like an M4.
Whoops, guessing I have my definitions wrong.