They are the grandfather of the Henry/Winchester rifles, at least mechanically, and they were made on contract by Smith & Wesson: their first job. As such, they are the foundation of TWO great arms companies.
I am extremely fortunate in that I managed to have a very nice one apart, once upon a time. Right now, it is hiding about 50 miles from here.
The ammunition was very low-powered and was made from the original Hunt "Rocket-Ball" patent. They used a hollow-based lead bullet with the powder charge pressed into the hollow base and a primer (much like a kid's toy caps) glued on. The hollow base of the slug did not have room for much powder, hence the very low power.
Tyler Henry modded the action, making it bigger and longer, then expanded the basic Smith & Wesson .22" rimfire cartridge, the one we now call the .22 Short, doubled it in size. Presto! You now have the Henry rifle in .44RF.
When Henry went broke at the end of the Civil War, Oliver Winchester bought the patents and most of the tooling, had Henry add a wooden fore-end so that your hands wouldn't get burnt. They added the "King's Improvement", being the loading gate on the right-hand side and you had the 1866 Winchester. Mod that to centre-fire and you have the Winchester 1873. Expand that to a .45-75 and you have the NWMP rifle. It was AFTER all that that John Browning got involved.
But the Volcanic was the start of all that....
