Got a new to me unfired Zouave 58cal. Measured and figured numerous times and always came up with .575 and .010 patch. Got the mold today and it throws .573-.574, good deal. Untill I checked the fit. Ball scrapes the riflings by about .002 all way round. Talk about luck. New mold otw. Going to have quite a collection if this keeps happening. Three groove not as easy to measure I guess. My overall ID was only off .001 but the land was, I thought .004-.005 was really .008. So much fun.