This sword bayonet was originally produced to fit the Brazilian Naval Rifle (almost identical to the British Pattern 1856 Sergeant's Rifle, made in Liege, Belgium); also believed sold with the US Model 1855 Colt Revolving Artillery Carbine (of which perhaps no more than 200 of these carbines were made). According to R.L. Wilson's The Book of Colt Firearms this was the "rarest distinct variation in the carbine series." He further states that, "bayonets measure 28-3/4" overall and are marked S&K (Schnitzler & Kirschbaum). They have iron cross-guards and brass hilts. Locking stud and spring of iron. Blade measured 24-5/16" in length by 1-1/8" in width. Some were marked F.H. on the ricasso, instead of the marking noted above. Produced in Europe, probably Germany."

According to the Standard Catalog of Firearms by Ned Schwing & Herbert Houze "these Liege made rifles were supposedly made for the Brazilian Government, but at the beginning of the American Civil War they were diverted to the United States, about 10,000 being imported."

The overall length of this example is ~28-1/2" but it is quite obvious that the tip has been impact blunted by ~1/4"; adding that back would show the overall length was - at one time - ~28-3/4". The would make the only discrepancy - and I believe Mr. Wilson may be in error - is the blade length. This example is ~23-3/4" in length, but adding the blunted 1/4" back would make this exactly 24"; if you also include the width of the cross-guard, which is ~5/16" thick, Wilson's measurement is quite plausible.
Reference pages 198 and 199, illustration A.

Scabbards were of black leather body with brass throat and drag.

According to Jerry Janzen, author of, Bayonets from Janzen's Notebook, this bayonet is also associated with a Brazilian Navy Rifle contract with Belgium, but produced in Germany. He also notes that these were used in the U.S. Civil War and "will fit the Colt Revolving Rifle."
It has a very British appearing cross-guard - utilizing a "cock's-comb" upper quillon-finial, used on similar period British bayonets - and is noted as an English Sea Service Bayonet for an Enfield musket by both Hardin and Kiesling, but Kiesling has stated that it "never saw service in the British Navy." Kiesling is the author of Bayonets of the World, considered the standard reference for bayonet collectors.

This bayonet is marked on the right ricasso with an anchor, flanked by two illegible characters.

This bayonet is marked on the left ricasso with S&K, for Schnitzler & Kirschbaum of Solingen, Germany (1811-1864).

This is another variation with the blade cut down to ~18". Also note the serial number on the pommel as opposed to serial number on the cross-guard previously noted above. It is my opinion that this example was one of the 10,000 diverted to North America during the Civil War.