Here is an interesting description of a 16 gauge Roper that Lock Stock and Barrel Investments had for sale. They speculate on what might be wrong with the gun for sale.
Mechanics: When the hammer is cocked, the bolt withdraws properly, but the cylinder spins freely instead of rotating one position. When the trigger is pulled, nothing happens. The hammer must be pushed down manually to get the bolt to close. The hammer has ¼ and ½ cock notches, but neither was intended as a safety. (When firing the shotgun when at full cock, the movement of the hammer and bolt would sometimes cause the shooter to move slightly – this could be remedied by lowering the hammer slowly manually until the cartridge was fully seated in the chamber and then pulling it back to half cock, and fired from that position). The hammer releases when the trigger is pulled: it just doesn’t move forwards. Also, it looks like the upper tang is cracked half-way across at the stock screw. We have not fired this shotgun.
Box, Paperwork & Accessories: Included with the shotgun are four steel reloadable cases. The steel cases provided a gas tight seal against the chamber. They could hold a paper cartridge and have a primer hand inserted at the back of the case before firing. The cases have been re-finished with a light brown cold bluing and show light pitting under their finish. One still has a fired primer in its primer hole. Three of the cases are in Good condition and one is in Fair condition with a small eroded spot on its front edge.
Our Assessment: The Roper shotgun was the invention of Sylvester H. Roper. He was a brilliant inventor who pioneered in the building of steam driven automobiles and motorcycles (or velocipede as he called them). He also invented a sewing machine and a hot air engine. He was granted a patent for the invention of a threaded shotgun choke and for his revolving rifles and shotguns. This is an early shotgun made when his company was still in Amherst, Mass. Apparently, the shotgun was purchased and engraved by Robert Symon, who was an Englishman who lived in Hermosillo and was a concessionary of the Sonora Mint. He was also one of two partners in a company that received a contract to build the Sonora railroad in about 1879, and then sold out to the Southern Pacific Railroad, who completed it. This shotgun has a four round revolving cylinder. When the hammer is cocked, the bolt withdraws, ejecting the fired cartridge and the cylinder turns to align a new cartridge with the bore. When the trigger is pulled the hammer falls, driving the cartridge into the chamber and firing it. Unfortunately, on this shotgun, the mainspring appears broken, because when the trigger is pulled the hammer must be pushed forwards manually, and when first cocked, the cylinder does not rotate automatically, although it does spin freely. The metal surfaces have been refinished, along with the buttstock. The shotgun is in about Fair condition. Most of the current finish has developed a patina, and there is pitting and handling marks under the finish. There are also spots of thinning on the barrel and receiver, with surface loss on the edges of the receiver and on the lower tang. The wood has a deep gouge on the right side of the buttstock with several thick drips of varnish on the right side and belly of the buttstock. There are also slivers of wood missing around the upper and lower tangs. The bore is gray with light erosion and a ring of moderate erosion near the muzzle. The screw-on choke is present, and the shotgun comes with 4 steel cases of the type used by this shotgun, which are very collectible in their own right. This is a nice find for anyone who collects Ropers. Far fewer of the revolving shotguns were made at Amherst than at Hartford, and there were fewer 16 gauge chambered shotguns than the more popular 12 gauge. This is a somewhat rare shotgun, and a forerunner of all semi-auto rifles and shotguns. We are sure it will appeal to the collectors despite its mechanical condition: someone will have the skills to fashion a mainspring and cylinder spring for this beauty.
RARE Roper Repeating Rifle Company Revolving Shotgun & 4 Shell Cases, MFD 1869-1876 Antique
