Shawn
Winchester's PG tangs were indeed made from standard tangs and bent. Somewhere I have a copy of the drawings for the fixture...It weighed about 5 tons.
That filler piece is press/shrunk fit into the lower tang, no rivets solder etc that I'm aware of.
Couple of things to keep in mind... plug all holes before bending, that keeps the holes from becoming out of round... also anneal the tang, and heat the tang to red/orange heat when bending...minimizes cracking.
Also your lever will need to be bent, and you will need to find a hammer spring for a PG.
V/R
Mike
