In discussing the rifling of .69 caliber muskets, some questions came to mind: 1. How were the grooves cut? By drill, lathe, mandrill? 2. How many grooves? 3. What was the twist rate, and how was it determined? 4. Musket barrel walls were pretty thin; how was the depth of groove decided? Were there tests to determine the strength of the rifled barrel? I realize these may be simple questions to the experts, but how about someone humoring me. Thanks. Stan