At the 1980 World Championship's of the International Muzzle Loading Committee (I.M.L.C.) held at Quantico, VA - they were not allowing any reproduction guns in those matches. However, Herschel House brought a number of folks dressed as Riflemen/Long Hunters who shot a Flintlock Team match with reproduction long rifles for an exhibition. They would have won the match with their score, had reproductions been allowed.
Not long after that, the I.M.L.C. authorized a "carbon copy" of all their matches and one could use reproductions. The matches where originals were shot were still considered more "prestigious," but at least reproductions could be fired since then.
As of the World Championships at Wedgnock, UK in 1998, the I.M.L.C.'s definition of "original" required an original lock and barrel, though IF the barrel was "re-rifled," it had to comply with the period rifling style. One of our Team Members had such a gun that failed "Scrutiny" (or the official inspection) because the rifling was supposedly not correct for the period of the rifle - even though it had been "freshed" or re-rifled in the 19th century. After I heard that, I asked to see the rifling and was highly upset because there was nothing wrong with the rifling for an early 19th century flint rifle, which that was. I was heading to the "Scrutiny" Area to argue with them, when our Team Captain stopped me and informed me he had already lodged an Official protest. That was the second time in that match that I was on my way to the Scrutiny Tent and our Team Captain had to stop me, the first was when a German deliberately broke the half cock on one of our Team Member's guns while "testing" it. Oh, was I riled up over that!!! I was able to fix it for our Team Member, though. We made sure he did not go back to the Judge who broke it and yes, I was standing there while it was inspected the second time by another Judge and it passed.
Oh, to pass as an original in that competition, it was not required the barrel and lock were made by the same maker. Everything else like a new stock and repro furniture were allowed as long as they were "correct" for the gun. I was surprised they allowed a new stock, but that is how they wrote the rules.
We even had one Team Member who shot a percussion single barrel pistol that had been cobbled together out of old mixed parts, probably in the late 19th or early 20th century. To be kind, it was not a pretty gun, but it shot extremely well. Even though it passed by the rules, I was a little surprised it passed Scrutiny with no problems.
Gus