Pikeman, not sure if this is useful or not but found the following info on a posting at www.horsesoldier.com. He mentions .82 rather than .818, however:

"Presented here in fine condition is a scarce and original Collins & Company-marked socket bayonet made for the Sharps New Model 1863 / New Model 1865 rifle. Of some 15,00 breechloading percussion Sharps rifles produced between 1859 and 1865, 4,400 rifles were fitted for a saber bayonet while the rest (10.600) were designed to take this style socket bayonet. Produced in Collinsville, Connecticut, this bayonet is virtually identical to the regulation US Model 1855 socket bayonet, save for a slightly larger socket and bore diameter and no blade markings.

Besides the markings, the Sharps bayo differs from the M1855 by having a higher bridge for clearance over the front sight. The flat of the blade shoulder on the weapon bears no stampings as usual. Muzzle area of the socket near the neck is stamped "C & Co" for Collins and Company and shows slight rust pitting. A small inspector stamp "M" is also found on the bayonet's shank. Triangular blade exhibits a tapered, spear shape and has a socket locking ring that helps secure the bayonet to the rifle / musket at the muzzle. This handsome specimen is 21" long overall with an 18" x ¾" wide blade that tapers to a point. Socket is 3" long with a bore diameter of .82". Blade, which does not appear to have been cleaned displays a dark gray mottled finish with a scattered speckles of peppery pitting and dark oxidation overall. No edge nicks. No scabbard.


This style bayonet is known to have been used not only on the Sharps New Model 1863 and 1865 rifles and the Model 1841 rifles, but also on the Confederate Fayetteville rifle as well. The main difference being their individual bore diameters. A fine, rare Sharps New Model Rifle 'Collins & Co.' bayonet specimen that would compliment any US military edged weapon display or bayonet collection.


(490-67) $495.00"