300 Blackout Barrels for the AR-15 Platform

The 300 Blackout AAC caliber round is one where the only part to change in the AR-15 Upper is changing to the 300 blackout barrel.  All other parts are the same in the 300 blackout rifle and the AR-15 Rifle including the bolt carrier group, upper, lower, magazine, stock, grip, etc..... If purchasing a separate .300 Blackout upper it can be swapped with a 5.56 upper and you can be shooting again pretty quick. One must be careful with with changing and not mixing up ammo from one upper to another because one is a 30 caliber round and one a 22 round. The gas system on the 300 blackout is pistol length due to the short burn time the pistol powder that makes up the 300 AAC round takes vs the 5.56 AR-15 Round.