The didn't make M1factory barrels with two grooves. Those are all made up barrels. I've seen them for carbines also, and they are also made up from '03-A3 rifle barrel replacements.
The didn't make M1factory barrels with two grooves. Those are all made up barrels. I've seen them for carbines also, and they are also made up from '03-A3 rifle barrel replacements.
Regards, Jim