Current .38-40 loads are downloaded for the older handguns being used. Really to keep your old '73 in good condition you ought to be shooting black powder with a lead bullet having a large grease groove. The first Winchester made for smokeless powder with jacketed bullets was the '94 in .30-30 which came out in that round in 1895.
As long as I am alive that gun will be shot very little, if any. I realize that jacketed bullet smokeless powder rounds are not good for it. I don't reload so to shoot black powder loads in it I would have to have someone reload them for me.
(Luke 11:21 KJV) When a strong man armed keepeth his palace, his goods are in peace:
(Luke 22:36 KJV) Then said he unto them, But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one.