This early Brown Bess Bayonet is simply marked "XIII" on the rear of the socket. There may be a small stamping on the blade, it is worn and hard to tell. Metal surfaces show a dark patina with pitting and wear. The socket has brass bushings added at both ends, these appear old, they must have been added to make it fit a gun. I am sure they could be removed. Bayonet measurements are: Socket Length- 3 7/8 inches, ID at Mouth-.935, ID at Muzzle-.865, OD Mouth-1.105, OD Muzzle-1.080, Blade Length-15 1/2 inches, Blade width-1 inch, Blade thickness-.400 inches, Shank-1 1/8 inches. The muzzle to stud measurement is 1 15/16 inches. Blade fullers are 12 1/2 inches long. These early (second) style bayonets from the late 1840s and early 1850s are rather uncommon, they were made to fit specific rifles, so seldom fit on a random rifle perfectly. An interesting bayonet for the collector. Free shipping.