The Nagant M1895 was a revolver designed in 1895 by Leon Nagant, for the Russian empire. The Nagant Brothers company was Belgian, but they were well known to the Russian military, because they were involved in an earlier competition to design a new rifle for the Russian military previously (the result of the earlier competition was the Mosin-Nagant M1891 rifle, although Nagant's contributions to the final design was very minimal).
The Nagant revolver design attempted to minimize the velocity loss, by making the revolver gas-tight as possible. We will discuss how this was achieved here.
Mosin-Nagant M1895 Pistol. Click on image to enlarge.
Image licensed under Creative Commons Attribution-Share Alike 3.0 Luxembourg license by user Mascemon @ wikipedia
At first glance, the revolver appears to have a pretty large cylinder gap, as can be seen by the image above. However, the revolver is built with a special mechanism, so that when the hammer is cocked, the cylinder not only rotates to the next chamber (just as any other revolver), but it is also pushed forwards toward the barrel, thereby closing the cylinder gap and creating a seal with the forcing cone at the back of the barrel.
Now, the cylinder is just one part of the gas-tight seal. Let's take a look at the unusual cartridge for this revolver. Here's a closer look at it:
From left to right, Nagant 7.62 mm., .32 S&W Long and .22 Long Rifle (.22 LR) cartridges.
Picture courtesy of Commander Zulu at Wikipedia.
The cartridge on the left is the one for the Nagant revolver. Compared to the other two cartridges, a few differences are clearly visible. Unlike the other cartridges, the Nagant cartridge fully encloses the bullet inside the cartridge case. Note that the neck case of the cartridge is crimped to a smaller diameter and the bullet does not protrude out of the end. This is part of the design. When the cylinder is moved forward into the forcing cone, the cartridge's unusual neck is forced between any gap left between the cylinder and the forcing cone. When fired, the neck expands into the forcing cone and fills any remaining gaps, making it even more gas tight. As a result of this, the Nagant M1895 does not leak much gas through the cylinder gap when it is fired, and the bullet comes out about 50-150 feet/sec (15-45 meters/sec) faster when it is fired.
As we saw in an earlier post, temperature has an effect on ammunition performance. By making the gas seal tight as possible, this revolver could perform better than other models, even in the middle of very cold Russian winters and with the types of propellants that were available in 1895. A couple of other side-effects are a result of this gas seal design as well. For one, it reduces the chances of injury to body parts in front of the cylinder, because the hot gases and particles don't come out of the side as much. Also because of the gas seal, the noise generated comes out of the barrel, which means that unlike other revolver models, this one can be fitted with a suppressor to reduce the noise.
The video above shows the unusual mechanism and cartridges in very good detail.
This revolver was used a lot by the Russian Empire and then, the Soviet Union, and is used even today by present-day Russian police, despite being out of production for about 60 years. It is regarded very highly in Russia for its toughness.
However, there are a few disadvantages of this revolver as well. The first is that it is much slower to load this revolver than other models. Because of its design, the cylinder cannot flip out of the side to load the cartridges simultaneously. Instead, the user must load and unload each chamber one at a time, via a loading gate on the side. Also, this ammunition does not have great stopping power compared to more modern cartridges. At one time, it was difficult for American users to purchase ammunition for this revolver, even though the revolver is pretty cheap to purchase (typically costs about $100). The trigger is also pretty heavy to use and accuracy suffers as a result.
Before we end this discussion, here's another video done by the same user above (hickok45), demonstrating the effectiveness of the unique gas seal of this weapon.