I would try JB bore past, take a couple of round balls and squeeze them in a reloading press or a vice until they are just over bore size so that when you drive them into the barrel they imprint all the rifling then center bore them to fir a 10-32 screw and use the screw to mount them on the end of your ramrod mark them where the front sight is and keep that same rifling in line with the same place all the time put the bore paste on and do 3 full strokes the put more bore past on after a few times you will have to squeeze them again and start over. This is the best I can do considering what you describe. Hope this helps Lee