I was browsing 'Forgotten Weapons' and immediately recognized the pistol with the lever Tuco picks up first on the 'junk table' in the gunshop where he accosts the owner to arm him for revenge against Clint.
It's a French designed, Russian built M1870 Galand Revolver. The lever moved the barrel and cylinder forward to eject the 11 mm Perrin rimmed cartridges.
It's a French designed, Russian built M1870 Galand Revolver. The lever moved the barrel and cylinder forward to eject the 11 mm Perrin rimmed cartridges.