These G&U percussion revolvers are rare species.
From what little I could find out Gregorelli and Uberti had their active partnership from 1959 through sometime in early 1963. That is after they made this deal with Val Forgett jr. about the supply of percussion revolver replicas in due time before the centennial of the Civil War and then some.
Their first 1851s did not have the Ormsby cylinder scene, no safety pins on the breech side of the cylinder and lacked the corresponding slot in the hammer. The only visible serial number is on the TG.
Currently known G&U marked pistols are replicas of the Colt 1851 Navy 7,5", 4 5/8" & 5,5" barrel variants, the CS pendant Griswold & Gunnison (brass frame & round barrel) 7,5" & 5,5" barrel variants, CS Leech & Rigdon 7,5" & 5,5" barrel variants, Remington New Model 1863 Army & Navy.
G&U also did a clone of the Sharps 4-shot pepperbox in .22 short. The specimen I have seen is from 1962. Which would make it the first cartridge gun with a Uberti name on it.
Would you care to share the date code of your pistol with us?
Long Johns Wolf