Single Action ..45 colt caliber centerfire. 6 shots. 4 3/4 inch round barrel. Barrel address "COLT'S PT. F.A. MFG. CO./over/ HARTFORD, CT. U.S.A." Also marked "(BISLEY MODEL)" and ".45 colt ." on left side of barrel. Fluted cylinder. Frame marked "PAT. SEPT. 19. 1871 / JULY 2. 72. JAN 19.75" and a "Rampant Horse on a Circle" Blue or nickel plated.
Bisleys were serial numbered in the range of 156300–331916, in the same sequence as the Single Action Army. ( and why i posted the army .. )
All Bisleys after No. 161,376 had "BISLEY MODEL" with the caliber stamped on the left side of the barrel, which is rare for older Colt revolvers. The most common calibers were .32-20, .38-40, .45 Colt, .44-40, .41 Colt, and the British calibers .450 Eley and .455 Eley. A total number of 44,350 were manufactured. The production of the Bisley was terminated in 1912, but the serial No. 331916 was shipped after the First World War. Most Bisley Standard Model Revolvers which were shipped to a United States address were not used for target shooting but for self-defense because the grip and hammer were ideal for fast shooting.
as a personal note
the few i've seen here a couple of the .45 where Oz versions of bubba'ed up from a smaller caliber ..
and both had the original cal. scrubbed off the barrel