Threaded 1:9 Fast Twist 18"Subsonic 10/22 22LR Accuracy Barrel® Blue (.920) Our EABCO Threaded 10/22 Accuracy Barrels® have threaded 1/2x28 muzzles to fit Muzzle Brakes and Suppressors. Custom thread protectors are included, order muzzle brakes separately. This "Fast Twist Subsonic" barrel features a 1:9 rifling twist to stabilize slower, subsonic .22 ammo such as: Aguila 60gr SSS Super Sniper, CCI Green Tag, Wolf Match Extra, RWS Target, etc. Subsonic ammo shoots quieter because the velocity doesn't break the sound barrier. The "slow and heavy" bullet approach puts a TON of whack on small game, too. Just ask any old timer about how his old 22 short seemed to kill squirrels better than 22 LR ammo. Subsonics do the same thing only they fit properly in a 22 LR chamber and give much better accuracy because of it. Subsonics are preferred by accuracy lovers because they don't lose any stability as the bullet slows down (High velocity ammo flutters as it passes through the sound barrier).