Special forces units utilize the CQBR for scenarios such as VIP protection, urban warfare, and other close quarters battle (CQB) situations.

The M4 carbine and M16 are not ideally suited for all missions due to their relatively long barrels, but the modularity of AR pattern rifles allows the operator to easily replace the upper receiver.

One of two proposed special mission receivers that were planned for inclusion into the SOPMOD Block II kit, the CQBR has taken off on its own.

The purpose of the CQBR is to provide operators with a weapon of submachine gun size, but firing an intermediate cartridge, for scenarios such as VIP protection, urban warfare, and other close quarters battle (CQB) situations.

Shortening the barrel by 50% from the original 20 inches (508 mm) pattern has a dramatic effect on the velocity of 5.56×45mm NATO ammunition.