I found this Hy Hunter .357 Magnum Western Six Shooter in a pawn shop and bought it at a decent price.
I had an old brass trigger guard in my parts box, from a
Colt 1851 Navy, original or replica I don't know. So tried it for fit, with a Colt 1873 backstrap:
I ordered a Hy Hunter replacement brass backstrap and a Uberti mainspring screw. I had already tried the Hy Hunter screw and found it not to fit.
A little careful filing:
And, I'm getting there:
The bottom backstrap screw collides with the mainspring screw, I'll have to shorten that. Then try to make grips!