Sig Sauer P320 – Modular 9mm Pistol | Omaha Outdoors
The P320 is Sig Sauer’s modular striker-fired pistol, built for adaptability and proven performance across law enforcement, military, and civilian markets. Our Omaha Outdoors P320 selection includes full-size, carry, and compact variants in 9mm, .40 S&W, and .357 SIG. The serialized fire control unit allows you to swap grip modules, slides, and barrel lengths without transferring the firearm, making the P320 one of the most versatile platforms available.
Whether you’re outfitting for duty carry, competition shooting, or home defense, we stock factory configurations and aftermarket-ready frames. The P320’s smooth trigger, low bore axis, and proven reliability have made it the U.S. Army’s M17 sidearm and a top choice for shooters who demand modularity without compromise.
P320 Build & Specifications
Modular Fire Control Design
The P320’s defining feature is its serialized fire control unit – the chassis that houses the trigger, sear, and striker assembly. Because this component is the regulated firearm, you can purchase grip modules, slide assemblies, and caliber conversion kits as accessories and assemble different configurations at home.
Swap from a full-size 9mm duty pistol to a subcompact .357 SIG carry gun in minutes, all on the same fire control unit. This modularity eliminates the need to buy multiple complete firearms when your role or carry preference changes. The same precision engineering found in Sig’s Sig Sauer Salient collaboration carries through to the P320’s machined internals, ensuring consistent performance across every build.
Grip Modules & Ergonomics
Frame Size Options
Omaha Outdoors stocks P320 variants in full-size, carry, compact, and subcompact grip modules. Each frame size accepts the same fire control unit, allowing you to tailor hand fit and concealability without changing your core pistol. Full-size models offer a 4.7-inch barrel and accommodate 17-round 9mm magazines, ideal for duty and home defense. Carry frames reduce grip length slightly for easier concealment while retaining a full-length slide. Compact and subcompact configurations prioritize deep concealment with shorter barrels and reduced magazine capacity.
Texture & Customization
Factory grip modules feature an aggressive texture pattern that provides secure purchase without abrading skin during extended wear. The interchangeable backstrap system lets you adjust grip circumference for smaller or larger hands. Aftermarket grip modules in different colors, weights, and textures are widely available, and installation requires no gunsmithing.
Caliber & Slide Compatibility
The P320 platform chambers 9mm Luger, .40 S&W, .357 SIG, and .45 ACP, with conversion kits available to switch calibers on a single fire control unit. A 9mm-to-.40 S&W conversion requires only a new slide assembly, barrel, recoil spring, and magazine – no frame changes needed. The same fire control unit cycles all four calibers when paired with the correct upper components.
Optics-ready slide variants ship with removable cover plates and direct-mount footprints for the Romeo1Pro, DeltaPoint Pro, and other popular reflex sights. Non-optics slides retain traditional three-dot SIGLITE night sights. All P320 slides use a stainless steel chassis with a Nitron PVD finish for corrosion resistance and reduced friction during cycling.
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Common Questions About the P320
Yes. The P320’s fire control unit is the serialized firearm, so you can purchase caliber conversion kits that include a new slide, barrel, recoil spring, and magazines. These kits are sold as accessories and let you switch between 9mm, .40 S&W, .357 SIG, and .45 ACP on the same fire control chassis. No FFL transfer is required for conversion kits since the fire control unit remains unchanged.
The primary difference is grip module size and slide length. Full-size models have a 4.7-inch barrel and full-length grip that holds 17-round 9mm magazines. Carry models use the same slide length but a slightly shorter grip for easier concealment. Compact models feature a 3.9-inch barrel and reduced grip length, while subcompact variants offer the shortest profile for deep concealment. All models use the same fire control unit and accept interchangeable grip modules.
Yes, all P320 magazines are cross-compatible with every grip module size. A 17-round full-size magazine will fit and function in a compact or subcompact grip, though it will extend below the magwell. This allows you to carry flush-fit magazines for concealment and keep higher-capacity mags as spares.
Most P320 models do not include an external manual safety. The pistol relies on a trigger safety, striker safety, and disconnect safety to prevent accidental discharge. Sig does manufacture P320 variants with a frame-mounted manual safety for departments and states that require them, but these are special-order configurations and not part of the standard catalog.
Optics-ready P320 models ship with slides machined to accept the Romeo1Pro and other reflex sights that share the same footprint. Adapter plates are available for different optic brands. If your P320 has a standard slide, you can purchase an optics-ready slide assembly as an accessory and install it on your existing fire control unit without transferring the firearm.
The factory P320 trigger breaks at approximately 5.5 to 6.5 pounds. This is consistent across all models and calibers. Aftermarket trigger kits are available if you want to reduce pull weight or change to a flat trigger shoe, though many shooters find the factory trigger smooth and well-suited to defensive and competition use.
Full-size 9mm P320 pistols hold 17+1 rounds with factory magazines. Compact models hold 15+1, and subcompact variants hold 12+1. Extended 21-round magazines are available for all models. Capacity varies by caliber – .40 S&W and .357 SIG models hold fewer rounds due to larger cartridge dimensions, while .45 ACP full-size models hold 10+1.