Osa (handgun)
| OSA | |
|---|---|
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PB-4M
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| Type | Non-lethal handgun |
| Place of origin |
 Russia
|
| Production history | |
| Designed | 1997-1999 |
| Specifications | |
| Weight | 0.4 kg |
| Length | 1.77" (45 mm) |
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|
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| Cartridge | 18×45 mm |
| Caliber | 18 |
| Action | double action |
| Feed system | 4 round chamber |
OSA (Russian: ОСА, "wasp") is a family of Russian non-lethal pistols that can be also used as flare gun, flashbang gun or starting pistol. The system consists of the gun (2-4 cartridges, laser target pointer, electronic ignition capsule), and various ammunition types.
OSA was developed in the 1990s by engineer-constructor and weapon designer G.A. Bideev (Г.А. Бидеев). It was designed and is manufactured by the state-owned organizations Federal Center for Research and Manufacturing and The Institute for Science and Research in the Applied Chemistry. The pistol is available in the civilian market.
The PB-4 is a four-barreled break-action gun. It has two horizontal "8"-shaped chambers in its aluminum chamber block, each housing two rounds. There is no need for a separate chamber for each round, because the gas pressure is contained by the cartridges' thick cylindrical case (the external case diameter is 18mm, while the bullet caliber is 15.3mm). This design aims to prevent the gun from operating properly if the round is unlawfully modified to increase its power. The cartridge case also performs the function of the barrel, with the bullet positioned deep inside and accelerating within the case. The front end of the case is level with the front end of the chamber block when in firing position. There is a four-fingered extractor in the central channel of the chamber block; the cartridge cases are rimless and have an extractor groove. The extractor keeps cases from falling forward outside of the chamber block. When the action is opened, cases are extracted backwards for manual reloading. The trigger and trigger guard are fixed to lower side of the chamber block.
The chamber block is locked to the handle block, which contains the locking surface, firing button (pushed by the trigger when the chamber block is locked), pistol grip, battery and electronics. The cartridge primers are ignited electrically, so there are four circular contact plates on the locking surface (contacting the case bottom) and four contact pins in the center of each plate (contacting the primer). On the trigger pull an impulse is generated. The electronic firing mechanism is able to send firing impulses in sequence to the chambers from 1 to 4 and to skip chambers with malfunctioning rounds to avoid misfires. The weapon is only capable of firing one round at a time. There are different models of PB-4; in some, the firing mechanism is fed by a battery, on others by a piezoelectric igniter similar to those used by kitchen gas lighters.
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Wikipedia