This groove is midway between the front sight and the flash-hider on the end of the barrel.
2. The cliche weapon of choice in first-person shooters.
3. The reason every prepubescent male in America thinks they know how guns work and how to correctly and accurately operate such weaponry.
2. Bob picked the M4 when he was playing Rainbow Six.
Prepubescent male 1: dude we knoe everything about guns from playing video games
Prepubescent male 2: the m4 is a 5.56 NATO caliber carbine used by special forces and SWAT teams, it features an integral flash supressor with a fully modular design base including the rail interace system, a collapsable stock, backup ironsights, and room for a mounted foregrip, 40mm m203 grenade launcher, flashlight, laser sight, and a nifty carrying handle!
Prepubescent male 3: dude we should join the special forces were so good