Guys! It obvious the producers found a COLLECTOR of flintlock rifles, because they needed a source for a Brown Bess for the film. They found it, but didn't realize that collectors may not be "Shooters ".
He was embarrassing in the film, and it was his own fault for allowing himself to be filmed doing something he was not skilled or trained to do. I suspect he didn't know HOW MUCH he didn't know. A lot of men I know, and have met over my life time, possessing MLers, appear to know no more about loading a MLer than Fess Parker did! I have met these men at the range, and after introducing myself, and showing them my gun, they will often admit that they really don't know what they are doing, and would welcome any instruction I can give them. After I explain the loading techniques that work, and the " whys" of the techniques, they then try them and are pleasantly surprised at how much better their guns fire. Then I let them take a shot with my gun. I make them use a rest, and they are very happy when they actually hit the target!
After watching his reaction to that first shot, which misses the small " barn " he was shooting at, I suspect you could count on one hand the number of times he every fired any MLer before that shot. I doubt seriously if he ever fired a shot from that gun before the film was made.