I'm trying to determine a little history on a Maynard 1873 that I just bought and hope that the Maynard collectors on the forum might be able to help.
The rifle has the usual patent markings on the left side and is marked 1873. The serial number (#27026) is marked on the barrel, lower tang, and the hammer. In front of the tang serial number is the number 1865. The 26" barrel is 40 caliber and the chamber is closest to the 40-60 Maynard. The pistol grip stock has the crescent butt plate and the rifle has both hunting sights and a tang mounted elevating peep sight.
A chamber cast shows the following:
Length   2.150" + .149"
Base      .476"
Neck      .460"
Rim        .149"
Grove     .422"
Lands       .403"
Twist        1-30"

My interpretation of the preceding is that a 1865 action was reconfigured to the 1873 style and set up as a 40-60 Maynard hunting rifle.
My questions:
1. Is my interpretation reasonable or is there an alternative explanation?
2. Does anyone know if a reproduction Maynard Schuetzen butt plate or the vernier tang sight is available?
3. What is the purpose of the two screws on the left side of the frame? The rear one looks as if it might be a retaining screw as it enters the round hole in the rear of the action. The screw below the hammer retracting lever screw doesn't look like it has any function.  
 


 

DB Thanks for your reply.
Yes the .135" rims would have resulted in excessive headspace. I made up some rims at .148" which worked well for headspace but my oversized chamber produced some funny looking cartridges using the 303Br brass. 
It sure is a fun gun to shoot. It may be easier to turn a cartridge to fit my chamber instead of trying to form them from available brass.
I wonder if I could ask a few more questions.
At 1200 o clock on the breach face there is a rivet or a plugged firing pin hole. I thought that the 1865 rifles were chambered for center fire rifles and I don't find a reference to this in any of my reference materials.
The Maynard catalogues indicate that the octagonal part of the barrel was 9" long and was fitted with a forend of similar length. My barrel has a short octagonal section (3.5") and a short forend. Were these older barrels that were rebored?
Were the S type levers linked to the pistol grip stocks or could they be ordered with the straight stocks?

   

DB Thanks again for the additional Maynard information. I think that you are correct that the barrel is one piece. I don't really understand the non standard chamber as the dimensions are beyond what I'd expect from wear.
You may also be correct about the stock being a replacement . After disassembly there is evidence of epoxy bedding but overall I think that both the metal and stock will clean up well. 
The current sights are fine for hunting but not ideal for the range. I've ordered one of the reproduction Beach front sights to replace the hunting front sight. I don't like the tang sight but don't want to modify it. Do you know if any of the reproduction tang sights will fit the Maynard's tang or current base? If a new base is required, are some easier to make than others? I won't be shooting this rifle over 100 yards. Do you have a recommendation as to the sight height?