Actually it's a 300/221 barrel, but it uses 300 Whisper loads and dies. Douglass 20" Stainless Steel barrel with a 1x8 twist, feed ramps have been throated and polished, threaded 1/2x28 with slightly recessed crown, barrel diameter turned down to .700 from the gas block to the muzzle. Gas block located at pistol upper length. Set-up perfectly for sub-sonic or suppressed loads. Includes barrel, custom gas block and gas tube. $200 plus shipping.