Cleaning rifle and rod tip comes unscrewed.
Pull plug and work some powder in through the flash hole.
Have second thoughts about shooting it out.
Dang---that sounds just like something I would do.
Is there a patch wrapped around the rod tip? If so you might try
a worm. Pour some Kroil down the barrel, let it soak a day or so,
and try to pull it out. If the tip is brass, try freezing the barrel
Your endmill idea wasn't all that far off. If you want to cut it out do this:
Turn a 4" piece of drill rod to JUST fit in the bore.
Bore one end 1" deep to leave a .025 wall. Bore other end 1" deep to 3/8".
On the .025 end, cut a series of saw teeth. File or dremel, doesn't have
to be pretty. not ^ teeth--you want the cutting face vertical.
"set" every other tooth "in" just a bit. Leave the rest straight.
Harden/temper the toothy end. Silver solder the other end to a chunk
of 3/8 round stock.
Now you have a long hole saw, that's "safe" on the OD. Lot's of
oil, turn it fairly slow, clear the chips often.