This barrel is for the M10/45. It is 4-5/8″ in length and threaded .578-28 TPI – it’s also known commonly as a Stubby Barrel. This barrel is ideal for your suppressor or other barrel accessory threaded .578-28. It’s also an option on the barrel we use on our Fat Ghost Upper Receivers. It is made of CrMoV MIL-B-11595 material with 6 – groove, 1:10 twist and precision air gauged with inert gas vacuum stress relieved after button rifling process. The finishing is manganese phosphate, the traditional dark gray/almost black parkerizing of the MAC series guns . These were profiled on centers to provide accuracy between bore and profile which has been a problem we’ve experienced with other manufacturers’ barrels in the past. These will fit Full and Semi Auto M10/45 guns. We also have A2 Birdcage Flash hiders threaded .578-28 that can be purchased separately.