Attached Link: http://www.wordiq.com/definition/M4_Carbine

Here's the newer M4 Carbine, which is what many Iraq soldiers are using, plus many SWAT outfits. M4 doesn't have the range of the longer barrel M-16 series, but since most combat now is Urban Warfare, that's not a big problem. Plus Army and Marines make much greater use of special sniper teams when they need the "long shot" capability.