The Trapdoor pictured is for sale locally the man thinks it is one of the rare carbine versions here is his description "It is chambered in 50/70. Very nice rifle for its age and still retains about 50% of the original bluing. These rifles where .58 caliber during the civil war then rechambered in 1870 to shoot the 50/70 cartridge. According to all the research I have done there was only 341 of these carbine models made with the 1863/1870 dates" I am thinking it is a cut down rifle.