M1855 vs. M1873 Bayonet for Trapdoor Rifle

Is there any way to identify an M1873 Trapdoor bayonet vs. an M1855 bayonet that has been "cold shrunk" to fit a trapdoor rifle?

My bayonet has a deep round punch mark above the "US" and also a tiny letter "A" on the socket.

TIA.
Jim

According to the best experts that I have talked to, no one has been able to definitely identify a Model 1873 made as such, compared to a Model 1855 that was converted. Quoting from American Socket Bayonets and Scabbards by Robert M Reilly "It is virtually impossible to differentiate between Type II and Type III". Type I was the M1855 modified by sleeving the socket, Type II was the M1873 made as such, and Type III was the M1855 cold compressed to M1873 dimensions. My guess is that ones that have additional markings such as you describe are Type III as it is unlikely that a Type II would have had additional markings other than the US. The additional markings are probably Civil War contractor variants.

Any credence to there being a "ridge" (formed by the cold pressing) on the CW converts? Thanks, Ray