Don't think that one has been rechambered to 45 colt. If it was, there would be either shallow rim recesses for the thicker 45 colt rims or the back of cylinder would have been shaved and stamping removed. It is possible the recoil shield was cut, but that is the worst method of modifying for 45 colt rim thickness.

Mine was modified by the slight rim recess method, which allows for the use of original 455 round because although the rims are thinner they also have a large OD so they rest on some of the original cylinder face.