As longcruise said, ignore the twist and shoot it. See what it likes. I have a whole closet full of flintlocks and can't tell you the twist of any of them, but I know the accurate load. Rifling depth is another thing people think they need. All you need is rifling deep enough to spin the ball. Maybe .006" to .008" or so. After that it is marketing by the manufacturers. I have been outshot many times by Douglas and Montana barrels with their shallow(by today's standards) rifling.