NEED HELP IDENTIFYING THIS BRASS BREECH RIFLE

I HAVE THIS BRAS BREECH, STEEL FALLING BLOCK, RIM-FIRE RIFLE, WITH AN OCTAGON BARREL. THE ONLY NUMBERS ON IT IS THE 2800 ON TOP OF BRASS BREECH. THE REAR SIGHT TANG HAS WHEN LAYING DOWN 100-US STAMPED ON IT, WHEN STANDING UP THE LOWER OPENING HAS 200-US STAMPED AT LOWERE PEEP SIGHT, THE TOP "V" HAS 500-US STAMPED UNDER IT.

I HAVE NOT HAD A CHANCE TO MAKE A CHAMBER CAST BUT THE BORE MEASURES .440, THE RIM IN THE BREECH WHERE THE CARTRIDGE WOULD SEAT IS .537. THE OCTAGON BARREL IS RIFLED, IT IS A RIM-FIRE, SINGLE SHOT.

WHERE THE STELL FALLING BLOCK LOCKS INTO THE BRASS BREECH ON THE LOWER TANG THERE IS A STEEL PLATE OVERLAYED WITH BRASS. EVERYTHING WORKSON THIS GUN. THE OWNER HAD PAINTED IT WITH RUST-O-LEUM MANY YEARS AGO AD WANTED THE OCTAGON BARREL BLUED NOW.. I JUST WANTED TO KNOW WHAT GUN IT IS BEFORE I BLUE IT AND FIND OUT LATER THEY WERE ACTUALLY JUST PAINTED.

I AM ATTACHING MY PHOTO-BUCKET LINK TO THE ALBLUM I SET UP WITH ALL THE PICTURES FOR YOUR VIEWING PLEASURE.

AGAIN ANY HELP AT ALL WOULD BE A GREAT HELP.

http://s1256.photobucket.com/albums/ii499/TRAKS1/BRASS%20BREECH%20RIFLE/

THANK YOU

KURT