When I first got involved with this fun, a fellow in our club who was a machinist made a tiny Lehigh rifle for his children to shoot. It was carved, inlaid, and engraved. It also had interchangeable locks, one flint and one percussion. It stayed percussion most of the time. He used a barrel (round, of course) that was salvaged from an old .22rf whose parentage I don't know. Both locks were made entirely with hacksaw and files and were tiny. The two lockplates were an exact fit. He said most of it was done with files in his recliner in evenings in front of the TV. It always amazed me whenever it came out. After his kids moved on to full-sized rifles, it mostly showed up at our two annual rondys and when we invited the public in. He would load and cap the little feller and with supervision and help let kids as young as 4 or 5 shoot it. The little grins were great to see.