Need help identifying - Rolling block saddle-ring carbine

[Johnboat 225]

I have one too. And the dimension sound similar. Mine chambers modern 43 Egyptian loosely and modern 43 Dutch Beaumont tightly. I say "modern" because both were made adapting and reforming another type of brass and may not be identical to original antique rounds. Both are tapered so the primer end is over 50 and the bullet end is 43ish. You can Google those and find schematics with dimensions. Not an expert. I only have the one carbine.

Your fore end retainer is not like mine. Mine has spring bar in the fore end wood that hold the one piece retainer in place. My retainer is an unbroken piece with no slot or screw. Yours looks like it is tightened or loosened by a screw on the retainer slot.

[rudybolla]

The breech of the barrel is marked 11 MANN , not H MANN, which means that the chamber was enlarged years ago to accept the more commonly available 11mm Mannlicher (Werndl) cartridge at that time. This was done to many formerly .43 Spanish rolling blocks in the 50s and early 60s.

[rudybolla]

Don't despair. You can probably get it to the range. Check with Buffalo Arms. They may have brass, dies, etc. If that fails, I have been in contact with a guy here in Texas who can make almost any case for you. Prices seem reasonable, depending on parent case, which in this case, might even be .43 Spanish.

[Dick Hosmer]

Admittedly not the easiest case to find, but, at one time, .348 Winchester brass (which is extrememly robust) was used to form such cases by slightly reducing the rear portion - around .75" or so - of the body of the case in a lathe, then fire-forming. As I recall, this worked very well.

[tjack]

I "lucked" into one of those in early 1987 except that mine was not marked "11 MANN". Got it home from the gun show and slipped an 11mm Spanish cartridge into the chamber. The Spanish cartridge kind of got lost in there. Made a chamber cast and....11 mm Mannlicher. This is the only one I've ever had so mine may be unique: the Mannlicher chamber reamer was run into the chamber just enough to open up the back end of the case. This left a double shoulder below the neck. Not a problem, just looks weird. Back in those days we could get BELL Basic cases and I used BELL 450 BASE NE. cases to make mine. My groove diameter is .441". The .439" Spanish bullet is a little small and the .446" Mauser bullet too large. With experimentation, I settled on the .439" Spanish bullet 20:1 and have to use black powder or Pyrodex to make the bullet expand (bump up). In those days the desert got rain. Many a jack rabbit met their demise on the receiving end of that carbine.
If I were you and I wanted to shoot it, I'd contact Buffalo Arms Co., order 11 mm Mannlicher cases and fire form them in your chamber. You shouldn't need dies. Of course, you will need to slug your bore to determine what bullet you will need.
Good luck!!