Have an old pistol that appears to be an original 75 Rem., It was found in a barn in NW Indiana about 25 years ago. I have been reading all the info that Pards have sent me but I just can't wrap my head around it. It is so rusted and pitted that I can't find any markings on it. It has the hammer style and cylinder ratchet measurement, as well as the pinch site of the first model. The cylinder openings measure .458 - .460 on loading end with .454 - .455 on the barrel end. Barrel slugs out to be .417 - .421. Any thoughts? Please!