Guys,
I do not know what the original alloy the Fry brothers used. However, it marks easily with my thumbnail so I assume it is pure lead and not an alloy. The Fry brothers rifling machine uses a similar cast guide for the rifling, it seems to be harder so it could be a lead - tin mix. For my freshing rod I tried several combinations of hot barrel - cool barrel; lead - alloy; hot melt and just barely liquid melt. It got rather frustrating as I got failure after failure. Things are easy if somebody else can show you how to do things. But when you try to figure How Did They Do That (HDTDT) you are in for a tough learning experience. To get a filled casting of the rifle bore I used pure lead, I also tried hard bullet mix but the mix did not shrink as much as lead upon cooling so I could not get it out of the barrel and I had to melt it out. To get the lead to work I cleaned the bore really aggressively - brushes, lead removal jags, etc. The old barrel was pitted, so a casting of the bore included bunches of interlocking points in the corrosion pits. What finally worked:
1. Clean, brush, scrape the bore until you arm goes numb.
2. Grease the bore with heavy automobile type grease - not oil.
3. Coat the bore with soot from an acetylene torch tip inserted into the bore, lots of soot.
4. Use brass for the connection part of the freshing rod.
5. Heat the pure lead to over 900F, pour it in quickly.
6. Gently push the cooled lead out. Never, never, never use a hammer to tap the end of the rod, this only obturates, expands, the lead. If you try to push the lead freshing rod out of the bore using a hammer, this does not work.
For the Fry brothers original freshing rod HDTDT wood to lead joint? Still a mystery to me.
Jim