so a carbine isnt a rifle? are you an idiot? n : a shoulder firearm with a long barrel and a rifled bore News to me. http://www.winchester.com/lawenforce...spx?storyid=11 They are different, but sorry I didnt notice that the bushmaster was 5.56 and not .223. Even though it says both, it is designed for the 5.56mm, which can generally accept .223 rounds. Anyways asshat, Colt made a gun named Colt model 720, the military adapted it as the M4. The link to the gun you bought is not a colt M4. Its a bushmaster. A knockoff bushmaster m4 is like buying a rolax watch instead of a rolex. (colt actually has a lawauit against bushmaster for this). Funny how you think your bushmaster m4a3 says colt on it. Just proves you dont have one. May say M4, but not colt. And here let me rephrase for your walnut brain. ITS SHORTER. Jesus.