The Royal Armouries has a lovely
17th-century flintlock revolver that is quite fascinating in its design and appears at least moderately practical, although quite expensive and rather heavy. The stats below use a 15 grain charge of black powder, but it's not significantly changed by having charges anywhere from 10-30 grains. It never moves from Dam 1, Rng 4 until the powder charge gets too heavy to burn completely in the barrel and Rng starts dropping.
Dafte(?) Flintlock Revolver, circa 1780 (12.6x8.0mm BP Ball)
Wt 2.83 kg, Mag 6, ROF SAR, Reload 1/chamber*, Dam 1, Pen Nil, Bulk 4, SS 1, Rng 4.
*loading with loose powder increases reload time to 2/chamber.
It's heavy, an awkward bulk for a pistol, slow to reload, and short-ranged. It's also far better than other pistols of the time.