The KAK Industry CQC AR-15 Pistol Buffer Tube Kit is for those wanting to make their AR pistol as compact as possible. The CQC buffer system is compatible with 556/223,300 BLK, 762x39, and 9mm. The weight of the buffer and spring rate of the buffer spring mirror a traditional carbine setup. Unlike most short buffer tube setups, the CQC is designed to function with any compatible milspec bolt carrier group. FeaturesCompatible with 5.56/223, 7.62x39, 300 Blackout, and 9mmProprietary short pistol buffer tube extends only 5.25" from the rear of the receiverHard coat anodizedFlatwire buffer spring for increased reliability and longer lifeProprietary short pistol buffer performs like a standard carbine buffer in combination with flatwire buffer springMil-spec end plateMil-spec castle nut