Build a custom AR22 conversion barrel. For use with AR15 to .22LR conversion kits only (.22LR to 223Rem Chamber Insert type). These barrels come with .217/.222 or .218/.222 bore and groove rifling but with a .223Rem chamber to accept various conversion kits out there but without sacrificing accuracy/velocity from using improper bore/groove diameter. No gas ports are drilled on these barrels. -----MUST BE USED WITH AN AR-15 to 22LR CONVERSION KIT AND FIRED ONLY WITH .22LR AMMO-----PLEASE READ BELOW IN OVERVIEW FOR MORE DETAILED INFORMATION.