Alright, guys. I went to Home Depot and got a Bosch 3/8” 18” drill bit. Turns out it’s tapered from the rear to the front of the bit, which miked at over .380”. Would not fit into the nosecap. Yeah... I’m not doing this I don’t think. I’m going to have the jag extend from the muzzle by approx 1” or a bit less. Reason is I’m planning to use an authentic style worm and puller set on a tapered tip. The worm and puller cannot be used as an extension because they’d either mangle the ball or mangle my hand depending on the direction!
I’ve also contacted someone about a reversible worm that matches the looks of one supposedly supplied with a rifle made in 1820.
Having the rammer extended “just a bit” from the muzzle seems to not be against historical correctness for my type of rifle. If anything, I’ve got 10 hickory rammer blanks coming from Dan Putz so have plenty to work with for experimenting.
Since I had the gun apart, I was able to check for markings (there was none, the maker may have removed them) and applied some Johnson’s Paste Wax to the underside of the barrel for added protection.
Thanks guys, was not about to start dickering with the nosecap or bore out more wood or anything crazy like that.