Howdy
I don't own any revolvers chambered for 44-40. Just too many variables what with chamber throats badly matched to rifling grooves.
However I own 4 rifles chambered for 44-40. An original Winchester Model 1892, made in 1894; a Marlin Model 1894, made in 1895; an Uberti replica of a Winchester Model 1873, made in the mid 1980s, and an Uberti Henry, made a few years ago. I have slugged all four rifles and can report that the 1892, the Marlin, and the Uberti 1873 all have rifling grooves on .427. Yes, the Uberti too. The Henry is the oddball, with rifling grooves of .429.
The Henry is the newest gun in the safe, previous to buying it I shot all three of the other rifles with .427 bullets. The '73 was shot most often in CAS, with nothing but Black Powder, so it became the rifle I used for load development. I soon discovered that its .427 rifling performed equally well with .427, .428, or .429 bullets. But .429 was pushing it a bit, because that size of bullet expanded the necks of my ammo enough that they became a little bit sticky in the chamber. For that reason, I usually only use Winchester brass, it is the thinnest at the neck, and the most forgiving with large bullets and tight chambers.
I was perfectly happy casting and sizing my Mav-Dutchman bullets to .427, but then came the Henry with its .429 rifling. I have since been sizing all my Mav-Dutchmen to .428. All four rifles like them fine. I cast my bullets from pure, dead soft lead, so they probably bump up a little bit in the Henry to fill up the .429 rifling.