A simple expedient is to take a take a peice of aluminium
, brass, or in extremis a peice of hardwood about a 1/2 inch thick. Take a drill bit the the shank just fits into the muzzle of you barrel and drill a hole through the material you have selected and either wobble the drill to enlargen one end of the hole or use a file to do so. Clamp the material to another piece so one end is blocked, fire up your pot with pure lead and fill the "mould" push out from small end and you have a 'make do' slug that will self direct into the barrel with enough bulk to give full impression of bore and grooves. Just remember to oil the barrel before sluging to make this easier.
Von Gruff.
