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.
Removable and Interchangeable PartsTo 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.
Px4 SubcompactThe Px4 Storm Subcompact is a compact Px4 chambered in 9 mm and .40 S&W. It has a DA/SA trigger. The Px4sc uses a tilt barrel system. Light-weight polymer construction with steel inserts, a modular trigger group, Picatinny rail on the chin, a plastic magazine loader and changeable backstrap options for the grip. It is intended for personal defense and law enforcement use with a focus on concealed carry
Beretta is marketing the PX4sc as the most advanced subcompact sidearm in existence. It is lightweight and small. The barrel is stainless steel, to help prevent corrosion from perspiration. The magazine release button is both changeable (two sizes included) and reversible. Finally Beretta’s patented SnapGrip Magazine Extender, extends the grip size down for a more secure grip.
Announced in late 2007, Project Allegiance has Beretta USA footing the bill for a $10,000 death benefit for any law enforcement officer who participates in the program. "Participate" means purchasing a Px4, and registering with the program. It's good for three years after the purchase. Beretta is also offering, as part of the benefit, free counseling, legal, and financial advice to the survivors of the officer who is killed in the line of duty.