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Old 05-20-2013, 07:30 PM
commando552 commando552 is offline
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There will be some loadings of the 9x19mm that are less powerful than the 9x18mm PMM, but generally no, the 9x19mm more powerful than the 9x18mm PMM. Although the case capacities of the two cartridges are similar (Parabellum is very slightly larger) the overall length of the Makarov is significantly less, meaning that if you want the same weight bullet it needs to be set back into the case farther and hence less capacity for powder. The more powerful 57-N-181SM round designed for the PMM is still constrained by this so is still weaker than a typical 9x19mm.

The 9x18mm is more comparable to the .380 ACP. In fact i think there are +P loadings of the .380 ACP that are more powerful than the 9x18mm PMM loadings, so there is no way it beats a 9x19mm. If you have read otherwise, I think you may be getting confused with the special Russian overpressure 9x19mm Parabellum loadings that are used in certain weapons like the Grach and GSh-18 pistols, and the PP-90M1 and PP-2000 SMGs.

Also, I think this special PMM loading was kind of a failure. Not only did you have the normal problems of introducing a new cartridge, but you had the additional risk of it being able to be chambered in older weapons, which would (and did) blow up whan used with it. The Makarov is a simple blowback design, so for the PMM what they did was to put spiral grooves on the inside of the chamber, which in effect acted like rifling on the expanding case and slowed its extraction. Due to the 57-N-181SM cartridge never being widely adopted, I think most PMMs were modified back to a standard PM style barrel without the grooves.
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