Is it close to impossible to have a metric thread cut onto the butt of a rifle barrel in the US? I'm planning my next rifle to be a Howa M1500 in 6.5mm Creedmoor. I want to pull the barrel and have a close-tolerance chamber cut into it, which will require the shoulder to be moved-up on the barrel by at least the length of the cartridge's neck. The tenon thread will then have to be lengthened so the barrel can be torqued back into the receiver. My concern is, can a modern lathe cut both a UNC or UNF thread and a metric thread? Are there various gears and transmissions that will allow such a thing? The receiver thread in a Howa is 26 mm in diameter x 1.0 mm in pitch. I'm wondering if I'll have to have an over-diameter barrel made, then have the 26mm thread hogged-out and a US thread cut into the receiver that will fit the thread that will subsequently be cut into the barrel. Yes, I know it sounds like the long way around the barn. But SAAMI chambers are too sloppy for me. I want no more than .003 inches of neck clearance as opposed to .006 inches. Am I making unnecessary problems for myself or chasing expensive ghosts?