FWIW, an article in our local gun club mag....hope it's not too long:
This is one of the more interesting revolvers produced. At first glance, it’s a typical strongly-made East-European/Russian revolver of only average fit and finish. And you’d be right. It was the Russian/U.S.S.R. standard sidearm issue from 1895 through WWII. Mine appears to be almost new. All numbers match, and an authentic holster, cleaning rod and lanyard were included in the purchase. The caliber is 7.62 x 38R ( approximately .311), and it’s a double-action type.
The unique feature of this revolver is that the Nagent cylinder moves forward when cocked and fired, theoretically sealing the breech between cylinder and barrel. Further, when cocked, the original Nagent cartridge brass, extending slightly less than 1/16” beyond the cylinder, also extends into a recess in the barrel and further “completes” the seal, (the bullet is seated completely below the open end of the brass).
In real-life practice, however, this “sealed breech” system is of dubious value, particularly in view of the modest power of the little cartridge. A 90 or 100 grain bullet rarely exceeds 900 fps, regardless of whether original or the shorter converted brass is used. In fact, the 7.62 x 38R was not used in any other Russian weapons, unlike the U.S. 45 ACP, or the Nazi 9mm Parabellum (now the 9mm x 19 used by U.S. and NATO troops) chambered in handguns as well as auto and/or semi-auto weapons.
This may be one of the easiest cartridge conversions ever. 32-20 brass (Star brand works best) is simply squeezed down in one step to .31 caliber, then loaded as usual. Lee dies and loading information were easy to find and .32 ACP bullets are readily available. An extra cylinder in .32 Auto was also included, but since loading cartridges was so easy, and worked so well, I’ve never attempted to fit it. I’ve loaded jacketed and lead bullets: both shot well, but 90 gr. .311 lead bullets made the smallest groups (3.4” @ 35 yds).
Several internet shooting forums advocate firing .32 S&W Long or .32 H&R Magnum through the original cylinder; certainly its robust construction suggests enough strength, but reports are that those ill-fitted cartridges split and aren't accurate.
Nagent revolvers “drip with history,” originally issued to Czarist officers and then later to Red Army officers and party officials. Because of its modest performance, you might think it was not suitable for combat use. However, there’s combat and there’s “Soviet combat”. Although it’s certain the Nagent was used against foreign enemies, many "authorities" agree a primary purpose was to “encourage” Soviet enlisted soldiers to battle. One source claims Soviet Army Nagent-induced casualties (usually in the back of the head) outnumbered enemy casualties by at least 10 to 1. For what it’s worth, a Nagent was Stalin’s personal firearm as well.