SuperC, That would be pretty tough to put date on it as the "swamp" that was used in the 18th century gradually kept getting straighter (less swamp)especially after 1800 when a lot of barrel factories began producing straight barrels in the late flint/ early percussion period. But I would say, as a general rule, if the barrel was hand forged it would have some swamp but if it was purchased from a barrel factory it more than likely would be straight. I have a southern (VA) flintlock rifle made sometime 1814-1834, it has a 44 3/4' barrel of 40 cal. The breech is 1.037-waist-.943- muzzle .971 and its a HEAVY one weighing in at 11 lb. 10 oz...Ed