Hello yeti5,

Taking a SWAG (Scientific Wild-Ass Guess) I'd say that what's pictured is a movie prop gun using either a Colt 1849 "Wells Fargo" or a Colt 1851 Navy cap and ball revolver as a starting point.  What's shown appears to actually be a cartridge conversion (to enable the firing of blanks?) as suggested by what appears to be a vestigial loading gate just behind the cylinder.  Curiously, the rebated cylinder (note how the diameter steps down toward the rear) would not be authentic to either an 1849 or 1851 Colt, which seems to reinforce the idea that this is a prop.  Google "Man With No Name Gun" to see a similar conversion that Clint Eastwood used in the 1960s spaghetti westerns.

Oh, and the cartridges?  From the fuzzy low-res image, they appear to be .32 ACP (Automatic Colt Pistol) rounds to my eye, as they seem to be too straight-walled to be 9x19 Luger rounds, and it's just possible to discern (or imagine?) a semi-rim on the rearmost cartridge.

Have a nice Monday morning!