G&G - Copy of the 1851 Navy, made by the South, brass framed, 36 caliber, dragoon style (round) barrel
1851 Navy - made by Yankees in the north, .36 caliber, iron frame, octagonal barrel.
BTW, While Bohannon's pistol was called a Griswold by more than one character in the show; the revolver being used is, in fact, a brass framed .44 caliber 1860 Army clone; and is not by any stretch of the imagination a Griswold.
The script writers for some unexplained reason attempted to impart some magical '.44 magnum super gun' aura around Bohannon's revolver by calling it a Griswold. Ooooooooooooooo.
Oh, yeah, Toolslinger. Nice piece. I've always liked the looks of the round barrel on the G&G and the L&R