The Beretta Px4 Storm is a semi-automatic pistol intended for personal defense and law enforcement use. It is available in full size, Compact, and Subcompact versions. The Px4 uses a trigger and safety system similar to the Beretta 92 and the Beretta 8000 series, though it is distinguished from its predecessors by its light-weight polymer construction with steel inserts, standard Picatinny rail, and swappable grip backstraps. The full size and Compact versions use the same short-recoil, rotating barrel action as the Beretta 8000 series, whereas the Subcompact uses the tilt barrel system.

Unlike the Beretta 92FS/96FS/M9/M9A1 and the 8000 series pistols, the Px4's trigger guard is rounded rather than squared. The polymer guide rod has a captive slide spring.

The full size and Compact versions have a spring-loaded disassembly bar, accessed via recesses on both sides of the frame, which must be grasped and pulled down to release the slide. This is different from the rotating takedown pin of Beretta's previous hammer-fired pistols, which the Px4 Subcompact retains.

The magazine holds the top round directly behind the barrel's breech end so only a slight feed ramp is needed. This allows the barrel to fully support the case. The 6-R rifling of the barrel generates counter-clockwise torque which is harnessed by the locking system to reduce the amount of pressure required from the rotating barrel lock's cam and pin system to affect unlocking. The steel transfer block's cam pin is 5 mm wide and 2 mm deep. The entire hammer unit mechanism can be removed from the Px4 as a single group. This allows easy access to the firing mechanism for cleaning.

Beretta designed the Px4 so that it would be difficult to re-assemble incorrectly after a field strip.

The Px4 originally featured an interchangeable, luminescent 3-dot sight system (coated in Super-LumiNova) for use in dark or low-light situations. With short exposure to any kind of light, the night sights' luminescence lasted up to 30 minutes.

Beretta discontinued the luminescent 3-dot nights sights for the Px4 in 2010, replacing them with standard 3-dot sights.^[2] The weapon also incorporates a Picatinny rail under the muzzle to allow flashlights, laser sights, and other accessories to be attached.

The full size (including the Px4 .45 ACP) and Compact versions are manufactured in Italy. The Px4 Subcompact is manufactured in the United States.

The Px4 full size was the first version available in 2004. Officially, it was offered in four different models:

• Type F: Single and double-action. Decocker. Manual safety.
• Type G: Single and double-action. Decocker. No manual safety.
• Type C: Single-action-only ("Constant Action" - hammer is in half-cocked position). Spurless hammer. No decocker. No safety.
• Type D: Double-action-only. Spurless hammer. No decocker. No safety.

However, the Type C and Type D models were usually sold to law enforcement agencies. Type F pistols can be converted into Type G pistols by removing a ball bearing in the safety/decocker unit or by changing the entire safety/decocker unit, depending on user preferences.

Occasionally, Beretta offers the Px4 full size with an INOX (stainless) slide.^[3]

The Px4 Storm Subcompact was released in 2008, initially in 9x19mm and later in .40 S&W. It has a DA/SA trigger. The stainless steel barrel is resistant to corrosion from moisture. It is intended for personal defense and law enforcement use with a focus on concealed carry.^[4]

The Px4 Subcompact is basically an updated version of the Beretta 9000. The two pistols even use the same recoil spring guide rod. Like the 9000S but unlike the Px4 full size and Compact, Px4 Subcompact uses a tilt barrel system and a rotating takedown pin. Also like the 9000S, magazines are available with the SnapGrip Extender base plate, which creates a longer grip profile.

Although the Subcompact is different from the larger versions in terms of its operation, it shares some interchangeable parts with the full size and the Compact, such as the safety levers, trigger, and magazine release buttons. Also, the Subcompact can use the longer magazines from the full size and Compact versions, and Beretta sells a magazine sleeve for the full size's 17-round magazine that basically extends the Subcompact's grip.

The Subcompact model has been discontinued as of 2023.

The Px4 .45 ACP was released in 2008 and is available only as a "full size" pistol. It has a reinforced body and is slightly larger than the 9mm / .40 S&W full size pistols to handle the higher ballistic power of the .45 ACP cartridge. The .45 ACP version was Beretta's entry in U.S. military's Joint Combat Pistol program.

The Px4 .45 ACP is available as a standard black model and as a Special Duty model with desert tan frame color, PVD coated magazines and internal firing control assembly, double recoil spring, and a longer barrel that extends beyond the slide. The Special Duty model comes in a custom case with lubricating oil, cleaning kit, three magazines, three back straps, three magazine buttons, and user manual.^[8]

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