Sorry for the omission there is always one missing, the internal dimension is 41.5 inches, 105cm. The two "slots" that you can see are strips of leather that run the full length of the case, the lines of rivets on the outside is what holds them in place. I agree that it seems rather short for a rifle case but the "bayonet" stowage, if thats what it is made me question its use.
I was told that the RussianCyrillic used in the words "From England
" was discontinued before WW1 hence the thought that the case was 1843.