The projectile is seated below the mouth of the cartridge, with the cartridge crimp sitting just above the bullet. When fired in the Nagant revolver, the crimp expands into the forcing cone, completing the gas-seal and ostensibly increasing muzzle velocity by approximately 75 ft/s.
The 7.62mm calibre was chosen, in part, to simplify the tooling used in barrel making and manufacture or projectiles—the Russian service rifle of the time—the Mosin Nagant M91 featured an identical bore diameter, being chambered for the 7.62x54R rifle cartridge.
Commercially manufactured and loaded 7.62x38R cartridges are difficult to find. Fiocchi of Italy manufactures cartridges in this chambering; they fire 98gr. FMJ bullets at about 850 ft/s (260 m/s), which works out to an energy of 157 ft·lbf (213 joules)—comparable to a .32 ACP semi-automatic. Prvi Partizan, a Serbian company, also produces a 7.62x38R load similar to Fiocchi's under the "HotShot" brand. There are also rumors that Wolf will introduce this calibre sometime in 2008.
Most commercially loaded ammunition for the Nagant, including Fiocchi and the "СССР"-marked yellow box imports, are target ammunition, and do not have great stopping power. The low power of these rounds has given the Nagant a reputation as an underpowered sidearm. However, the original military ball cartridges fired bullets in the 100 grain range at up to 1,100 ft/s, making them close to the .32-20 Winchester and .32 H&R Magnum in power. These original military ball rounds are very hard to find and are considered collector's items.
One advantage of the round, if proper brass can be found, is that it leaves the chambers totally clean, and there is no need to scrape lead and powder residue out.
Many users of this calibre handload their own ammunition, though the proper brass cases are also expensive and difficult to come by. However, Starline has been developing and perfecting brass for the cartridge, and handloaders have had success using dies for the .32-20 and .30 Carbine to handload the rounds. 32-20 brass cases are inexpensive, readily available, and can be reformed and used safely in guns chambered for 7.62x38R, but the resulting cartidges are too short to achieve the gas seal. Cut down 223 brass reformed in 30 carbine dies can be utilized to load for the Nagant also. These will achieve the gas seal.
Three other cartridges—.32 S&W, .32 S&W Long, and .32 H&R Magnum—will also generally chamber and fire in the revolver, but will not achieve the gas seal. The case head of the .32 S&W/H&R is about the same size as the case diameter of the Nagant cartridge, so the case head will sometimes actually end up moving into the chamber, thus preventing an adequate primer strike. Due to the dimensional differences between these cartridges and the original 7.62x38R cartridge, this practice is done at the shooter's own risk. The most common anomaly when firing these cartridges is bulged cases.