that would be a good avenue. Simply boring out a .44 cylinder leaves a bit to be desired as the .44 Mag. case is bigger on the front end than a .44-40. Starting with a .41 Mag. and chambering it properly would be a pro method. The .44 barrel of .429" is no problem as the .44-40's are all over the place as to actual bores. I know some books say .427" but who knows what they ended up being. The .429 bore would probably perform with the soft and easily upsetting lead bullets to shoot them fine.
I re-chambered a .44 Mag. cylinder to .44-40 and made sort of a hybrid. It's shoots factory Cowboy loads fine and I re-load the sort of blown out .44-40's with .430" bullets. I've even hot rodded them to impressive performance, since they would not fit in a normal .44 revolver or lever gun. I used a (0.430") colleted reamer to keep things central and it worked! But it only impressed me.
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