Hi Jeff,
I may have seen another stamped 45 S&W over the years that was re-chambered to 45 Colt but can't recollect for sure.
Take a 45 Colt cartridge or case with you to check the chamber length. It's almost a certainty that it's converted to 45 Colt.
Hopefully it was re-chambered correctly by recessing the chamber mouths .020" to obtain proper head space for the thicker Colt case rims, instead of shaving the cylinder face or recoil shield.
By recessing the chamber mouths the cylinder would retain the ability to still shoot .455 because of its larger diameter rim that will not fit into the smaller diameter 45 Colt rim recesses.
Let us know what you find out.
As you likely know, the only factory chambered 45 S&W Special revolvers were pre production Triple Locks submitted for the Army trials of 1906. None of those had a caliber marking.
I and one other forum member each chambered a triple lock for the 45 S&W cartridge but didn't caliber mark them. Both of our triple locks were in need of a barrel and cylinder so neither gun was desecrated. I used a new old stock triple lock 455 barrel that I'd had for years. I used a later pre war 45 ACP cylinder and extractor rod with its barrel knob which replaced the TL rod. I used .45 colt cases cut to the 45 S&W length and taper crimped that head spaced on the 45 ACP shoulders in the chambers just right, so the cylinder did not need modification.
