COLT - AR6721 Receiver Extension

This is the genuine article. Fits perfect, no wiggle or slop when using my SOPMOD stock.

Yes, it's four positions. Yes, there's a grey dry lube spray applied to the inside of the tube (as of 12/30/2019). Don't let the "AR6721" name confuse you, this is the same carbine buffer tube on the 6920, issued M4A1s, and everything in between. This 7075-T6 buffer tube will handle the repeated beating of the buffer and BCG and any "mortaring" of your rifle in the case of a malfunction. Colt 7075 buffer tubes have a high strength and stress resistance compared to other common 6061 tubes. Would recommend

Well, say what you want about Colt, but their parts are hard to beat. Over the years of building AR pattern rifles Ive seen so many different reciever extensions. This one is my requisite now for any rifle I build. 4 position is more than adequate so dont get deterred by that. I deliberately had 7 shooters of various sizes adjust the length of pull to accomadate their preferences with NO complaints at all. Novice to Ranger. High quality and fits like a glove for the MFT, MagPul, and B5 stocks I tried on it for fit.

Machining of the threads, especially the machining of the threads is second to none. The inner surface is as smooth and perfect as the outer surface. The coating of the inner surface is nearly exactly same as the outer surface. Only a small coating imperfection exists at the very end inner part of the tube which makes no sense for function. Other than this small imperfection, this buffer tube deserves every penny you pay for. Yes... I highly recommend this product especially to whom are looking for a buffer tube for the rifles that will be used for serious purposes.