As Lee said, plus it has an altered front sight. Originals were a half-moon sight. We can help dating the revolver if you supply the serial number?
Have you tried a 44 Russian cartridge for fit? It was not uncommon to find these in 44-40 as well. 44 Russian will loosely fit in a 44-40 chamber, but a 44-40 will not chamber in a 44 Russian. Cylinder looks like a 44 Russian, but hard to tell for sure. Short cylinders for Russian caliber are 1 7/16", while 44-40 cylinders are 1 9/16".
Lastly, I am curious if the right stock has a number stamped or hand written on the underside?