The Smith & Wesson Model 320 Revolving Rifle is one of Smith & Wesson's rarest products. With less than 1,000 examples produced over 8 years, the Model 320, which combined the multiple shot cylinder and single action mechanism from a revolver with the accuracy of a rifle, is one of the world's most desireable firearms, frequently selling for figures around the $100,000 mark.
As with the earlier Colt Model 1855 Revolving Rifle (produced from, as the name suggests, 1855), the Model 320 took its basis from one of Smith & Wesson's revolvers, the Model 3 (or this atleast was used for the basic design of the mechanism). As such the Model 320 is a single action rifle/revolver with a six shot cylinder, like the Model 3. Furthermore, Smtih & Wesson remained true to form, meaning that the Model 320 is also a break top revolver, with the barrel and front part of the frame hinged to allow acess to the rear of the cylinder.
Unlike the Model 3, however, the frame is attached to a 16in (or in some cases 18in or even 20in) long barrel which has also been rifled. The grip has been cut with a slot to allow the buttstock to be fitted or removed (the idea being that the detachable stock would mean the Model 320 was easier to carry). Other minor modifications have been made to the hammer, trigger and cylinder, while the barrel is fitted with an interchangeable blade sight at the front, while two folding leaf sights form the rear sight.
The Model 320 was given its name, Model 320, by virtue of firing the .32 calibre cartridge produced by Smith & Wesson at the time. This cartridge proved to be more reliable (and hence made the Model 320 more reliable) than the older Colt Revolving Rifle's .36in (or .44in, or .56in) musket ball.
Yet, the Model 320's cartridge remained a blackpowder cartridge, although that did not mean that a potential failure of the Colt (whereby excess powder from a previous shot ignited the other cartridges in the cylinder, spitting molten lead and burning powder onto the shooter's forearm) would also plague the Model 320. Instead the issue that using blackpowder caused for the Model 320 is that the powder would often ignite around the cylinder, spitting forward around the front of the cylinder, burning the user's hand.
The Model 320 is recorded as being Smith & Wesson's rarest production firearm, having had a total production run over 8 years, totaling 977 rifles. As mentioned earlier, this has meant that prices (on the rare occasion that a Model 320 has been sold at an auction) frequently close around the $100,000 mark. Each of the 977 Model 320s are marked with a serial number (from 1 to 977), with 840 originally sold in the US, the rest exported.
The closest contemporary firearm to the Model 320, at the time, was the Colt Model 1855 Revolving Rifle. Other firearms, particularly around the time of the Colt, tended to be single shot rifles and hence gave the handgun manufactures a potential market to exploit. However the safety issues raised by the design of the revolver and its use of blackpowder at the time (which was largely unavoidable) meant that the concept never really took off.