[hstout1143]

What is the difference between an AR-15 and an M4? What calibers can be shot on an AR-15 platform? Is a 6.8 spec too long of a round for an AR-15? And the most important question of all, Why does 76Highboy paint his nails?

 

[Albtraum]

M4 Carbine is an M16 with a 14" barrel and collapsible stock. Select fire from semi-auto, 3 round burst, and full auto.

AR15 is the civilian version of the same M4/ M16 platform. Of course, semi-auto only. Barrel lengths of at least 16". AR15's range from 223 Remington, 5.56x45mm, .45 ACP, 5.7x28mm, 6.5 mm Grendel, 6.8 mm Remington SPC.

AR10 variants can be chambered in .308 Winchester, .300 Win. Magnum, .338 Lapua, and there are even .50 BMG ARs.

 

[aa1911]

the selector lever moves one more notch on the M4... the only important difference. a couple inches of barrel I suppose if that matters to anyone... technically M4's are either Colt or FN.

I'm afraid I can't help you with the other question though....