M16 vs M4 (20 inch vs 14.5 inch) (Rifle vs Carbine)

[tac40]

I use a Colt M4 w/ 14 1/2 bbl at work. The carbine is a very practical rifle, with good ammo and glass you have a good primary weapon system. The big advantage is compactness of the 14 1/2, it's a bit easier to get the carbine in and out of cramp places. Personally, I would go 16 bbl w/ 1X7 twist over the 14 1/2-a bit of velocity gain.

As M24 & Capt Kirk said, consider your options with different uppers. Consider a 2nd upper in 6.8mm. As a SHTF weapon, the AR can be modified to fill various roles. Good luck.