The Beretta Px4 Storm is a semi-automatic pistol manufactured by Beretta of Italy and intended for personal defense and law enforcement use. The Px4 uses the same short-recoil, rotating barrel lock as the Beretta 8000 Models and uses exactly the same operating system as the M9/92/96 series, while being completely different in design from either. Light-weight polymer construction with steel inserts, a modular trigger group, fully enclosing slide, Picatinny rail on the chin, and changeable backstrap options for the grip are a radical departure from previous Beretta designs.
Unlike the Beretta 92/96/M9 series, the Px4's trigger guard is rounded for better concealed carry. The takedown pin of earlier models is replaced by a spring-loaded bar, accessed via frame recesses at both ends, which must be grasped and pulled down simultaneously to release the slide. The slide spring is doubly captive, being inserted approximately an inch into the transfer block at one end and a receiving hole in the front of the slide at the other. It is a self-contained assembly, completely captured by the polymer guide. 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 5mm wide and 2mm deep. The entire hammer unit mechanism can be removed from the Px4, without the use of special tools, as a single group. This allows easy access to the firing mechanism for cleaning. The Px4's design makes it impossible to assemble incorrectly from a field-stripped takedown.
Px4 features 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 lasts up to 30 minutes. The weapon also incorporates a Picatinny rail under the muzzle to allow flashlights, laser sights and other accessories to be attached.
To aid the versatility of the Px4, a number of parts were designed to be removable and interchangeable. These parts include the backstrap, the magazine release button, the slide catch and the hammer unit mechanism. The backstrap is available in three sizes: slim, standard and oversized. The magazine release button can be mounted on either side of the weapon and replaced by one of three types: standard, large or combat (extended). The standard slide catch can be replaced with a slimmer version to avoid snagging when the weapon is drawn quickly from a holster.
The Px4 is available in four models:
Type F: Single and double-action. Decocker. Manual safety.
Type C: Single-action-only ("Constant Action"). Spurless hammer. No decocker. No safety.
Type D: Double-action-only. Spurless hammer. No decocker. No safety.
Type G: Single and double-action. Decocker. No manual safety.