Colt Model 1855 Revolving Shotgun with large frame and .75 caliber (10 gauge) barrel. Manufactured in 1860, this early production revolving shotgun (serial number 51!) has the scarce small oval trigger guard and walnut stock with no checkering on the wrist. The barrel is round with a 3 /12-inch semi-octagonal section at the breech. The barrel has nickel-sliver front sight bead and an iron under-rib with two iron pipes. The shotgun is fitted with a gutta-percha cleaning rod with nickel-silver tip. The shotgun has a five-shot, fluted, cylinder, top strap with a sighting groove and loading lever with mushroom-shaped head. The walnut stock and forearm have a varnished finish. The stock has an iron shotgun buttplate. The wedge-fastened forearm has a nickel-silver tip and oval wedge escutcheon. The barrel, frame and cylinder have a high polish blue finish. The loading lever, hammer, trigger guard and buttplate have a color casehardened finish. "COL. COLT HARTFORD CT.U.S.A." is stamped in the top strap sighting groove. "COLT'S PATENT/NOV. 24th 1857" is roll-stamped on the left side of the frame. "PATENTED SEPT. 10th 1850" is stamped in one cylinder flute. "75 CAL" is stamped on the left side of the trigger guard bow. The serial number, "51" is stamped on the underside of the frame and the underside of the trigger guard. The heel of the buttplate is numbered "36". Colt manufactured approximately 1,100 Model 1855 Revolving Shotguns between 1860 and 1863. Only a few .75 caliber shotguns were fitted with the small oval trigger guard and uncheckered stocks.