yeoman
It is really east to give advice when you do not have the object... so here goes...
Question #1: should I remove the rib or trim it on the barrel? I may be able to slip a piece of paper between the rib and barrel and cut with a hacksaw and/or get nearly through and "tear" or flex it off. I'm concerned about mucking up the rib screws - never had one off.
Remove the under rib and cut it where it needs to be... use cold blue to bule the end... The screws on that new barrel will not be that tight. I am sitting here with mine in my lap right now. Get a screw driver that has a clean tip and fits the head of the screw. Apply a forceful downward pressure on the screwdriver before turning the screw. Just loosen it do not take it completly out until you have all the screws loose. Gm did not use a lock tight to hold the screws in.
Question #2: would you widen the $25 tang slot or narrow the $180 barrel breech hook, keeping in mind if I widen the tang slot the 54 cal barrel will be 1mm smaller than the slot should I choose to use it. Is that a big deal?
No doubt! widen the tang slot. It really should not take much and it should not cause a problem with the other barrel. 1mm actually a 1/2 mm on either side will not effect the other barrel that much. The only thing the left right movement in the tang does is to help provide alignment of the hammer striking the nipple.... this may be actually your biggest problem when placing the new barrel. One thing you could do is to remove the tang and set the barrel in the channel and see how the alignment might occur. -
After reading the other folks thoughts - i still would modify the tang vs the $250 dollar barrel - you can always get another tang. After you have removed the under rib and the tang and before you cut the under rib, set the barrel in place check the wedge alignment - put the wedge in place and lower the hammer on the nipple what does this look like...
I have a good bench vice and numerous files, am a reasonably accomplished craftsman and would like your thoughts.
This statement tells me you can do this and you say it with authority - so I am confident.
Start with the under rib project then move to breech end...
You can get TC tangs from TOTW for $12.95
Go for it... keep asking questions as you need to. The most critical thing in this project is the alignment of the nipple and hammer. By placing the barrel in the channel with out the tang and then closing the hammer on the nipple will tell you a lot...
Actually the biggest thing might be the alignment of the wedge and under key - check that also...