Hi rye if you smoke rollies grab a paper out and use it,about one and a half thou don't know how you say that in metric.We used to use that method free floating sporting firearm barrels.I know there's plenty of apps around for converting af to metric re thread sizes but everytime you look at the chart it leaves you with a vague headache,man i wish and am going to tool up so i can cut some half decent threads for my saito exhaust systems!!
