Not for an AR this is for a Bolt Action receiver such as a Remington 700 for example. Proof Research will put “Bolt” in the description meaning it’s a blank for a Bolt action rifle and has to be chambered/fitted to your rifle by a gunsmith. The following description is from the Proof Research website.
”By designing a bolt action barrel blank, we have opened up countless options for chambering in your favorite caliber and having the ability to fit a large variety of actions. Our bolt-action barrels are available in a variety of calibers, lengths, contours and twist rates. Your bolt-action barrel will arrive ready for thread and chamber by your gunsmith.”