The Makarov PMM updated self-loading pistol
By the late 1980s, a mismatch between the capabilities of the in-service pistol system and the changed conditions for operational of side arms — a wide use of body armor required increased penetration and better accuracy of fire — had become evident, in the early 1990s a PM pistol derivative0 chambered for a new 9x18 PMM high-power cartridge, was proposed for a competition for a new army pistol. The new shape of the bullet weighing 5.54 g (as against 6.0 g for the old bullet) and a higher muzzle velocity (420 m/s) combined to ensure belter ballistics, higher penetration, and lower ricochet probability.
Izhevsk Mechanical Plant's designers B. M. Pletsky and R. G. Shigapov developed the upgraded Makarov PMM pistol (56-A-125M) chambered for the new round. The pistol has been in production at Izhevsk Mechanical Plant since 1994.
Externally, the PMM differs from the baseline Makarov PM in a larger notched pistol grip to ensure greater stability during a shot. The PMM can be fitted with a single-column 8-round magazine or a double-column 12-cartridge magazine (the variants are designated PMM-8 and PMM-12, respectively). Magazines with a capacity of over ten rounds are typical of modern combat pistols. A smooth transition of the double-column magazine into a single-column neck allowed designers not to modify the magazine cavity and the slide.
Three spiral grooves on the chamber wails enabled the PMM pistol lo fire both the high-power and standard cartridges. When a shot is fired, the cartridge case walls are pressed into the grooves by the powder gas pressure - this increases the resistance to the cartridge case's backward motion, while preventing it from a cross break. At the same time the higher the bore pressure, the greater is the resistance, meaning that the high-power cartridge generates the required bore unlocking delay. When the PMM pistol fires standard 57-N-181S rounds, the chamber grooves offer almost no resistance to the cartridge case when it moves longitudinally to the rear.
Incomplete disassembly of the PMM pistol
A modified pistol grip can markedly improve the accuracy of fire. Some experts estimate the accuracy of fire to be 1 2-fold greater while others (mostly the experts at IMZ itself) evaluate the improvement at 2- to 2.5-fold.
However, the PMM cartridge has never become common use. Aside from the common problems typical of the 1990s hindering putting the new round into batch production, there were certain concerns that standard Makarov PM pistols. too, would be used to fire the high-power rounds which might lead to accidents and injuries. Since the 9x18 PM cartridge remained the basic standard round, the spiral grooves were removed and the PMM chamber became similar to that о I the PM pistol. The upgraded Makarov PMM pistols were delivered to the Ministry of Interior, the Federal Guard Service, and also to the Armed Forces (in limited numbers).