I am not the worlds greatest expert in the different models out there, except for the basic ones, like a Colt navy versus a Remington new army, or a walker versus dragoon... etcetera.
I really am not familiar with a Griswold Gunnison model at all, but, there is a tendency, amongst the Itallian reproduction gun makers, to come up with somewhat "fictionalized" models, that, actually were never really used at all. For example, an 1851 Colt Navy, was, by definition a 36 Caliber Brass framed pistol, in the old days... But today, you will find, steel framed 44 caliber versions all over the place !!! LOL !!!
Some of these are actually historical representations of not very commonly made or used guns, and some of it, is marketing, by the manufacturers, to sell more guns...
Perhaps another member here is more informed on the Griswold Gunnison model than I am.
Sincerely,
ElvinWarrior... aka... David, "EW"