Ed:

This will be a quick answer as most of the history of the double rifle is beyond me. I mentioned to Editor Heath I would share all of the questions and answers with him. I hope he does not fire me when he sees how little I know about this topic! That said, a close friend here in Alaska has a marvelous collection of double rifles including several flintlock doubles. Then, of course, was the natural progression to caplock or percussion.

I do know that in order to double the firepower in the muzzle-stuffing days that a second barrel was the only way to go. I do not know if the twin tube design went as far back as the wheel lock and the match lock. I have seen only side-by-side double rifles in flint lock and cap lock. I do not know if an over and under doubles were produced in this early period. (I just learned of a percussion double in .600 by Greener!)

Good shooting,

Cal