Your info narrows it down a bit more, as it is either a model 1893, or 1894 Marlin, made around 1900. The caliber marking was on the top flat of the octagon barrel, just in front of the receiver. They are very faint often, and may need a magnifying glass to be seen.
The odd part is that both of these models had the top tang marked with a model designation after the first year of production. I've seen a few that weren't marked, but all had serial numbers indicating they were early first year guns.
If it's a model 1894, then it would be a .32-20, but if it's a model 1893 it could be a .32-40, or .32 Win. Spl. The 1894 receiver is about 4.75" long from the front whee it meets the barrel, to the spur of the hammer (with the hammer down) The 1893 measures about 6" to the same points.
If it's the longer 1893 action, then you can check the chamber by pulling the lever and bolt. Simply remove the lever pivot screw, and pull the lever out the bottm after opening it. Then pull the bolt straight back.
With the bolt removed use a light to examine the chamber. If it is a model 1893 .32 Win. Spl. it will be chambered for the bottlenecked case, and you will see the step in the chamber. If it's a .32-40, then it will be chambered in that striaght walled case, with no step.
If you get a picture, send it my way, and I'll try to help more.
marlinguy@juno.com
Hope this helps.
