I am selling this barrel as i hardly ever shoot the upper. This is a Bartlein blank chambered by PF and nitrided afterwards. Gas block is .750, 5/8x24 muzzle thread, 1:8 twist. I would estimate i have around 200 rounds through it. This is a high end estimate. $575 delivered to your door. I take paypal or venmo. I can send you more pictures or answer any questions you have. Thanks!