m16 upper and lower matching

[jundeleon]

Will a complete AR/m16 rifle upper assembly work with any complete lower assembly?

Can you simply swap an upper assembly with a 24 inch barrel with a carbine or 14.5 configuration upper and the rifle will function reliably?

[JimBianchi]

yes

[isuzu]

Semi-Auto ARs have different bolt carriers and hammers than a full-automatic M16 and its variants. The firing pin is also different. The AR has a smaller firing pin collar compared to the M16's.

24" AR barrels (most of whom are match barrels) are generally chambered for the .223 unless specified as a 5.56mm chamber or a Wylde chamber which could use both .223 and 5.56mm ammo. If the chamber on the 24" barrel is a .223, you might want to use .223 Rem. ammo. Using 5.56mm might cause your rifle to experience overpressure problems.