The Sig Sauer P320 Full Size is a striker-fired semi-automatic pistol chambered in 9mm Luger with a 4.7-inch barrel, 17-round capacity, Black Nitron stainless steel slide, and polymer frame. At 29.5 oz and 8 inches overall, it's a full-size service pistol. Two magazines are included. 
 

Key Specifications 

• Manufacturer: Sig Sauer 
• Model: P320 Full Size 
• Caliber: 9mm Luger (9x19 Para) 
• Action Type: Striker 
• Capacity: 17 rounds + 1 in the chamber 
• Barrel Length: 4.7 inches 
• Overall Length: 8 inches 
• Weight: 29.5 oz (approximately 1.83 lbs) 
• Finish Color: Black Nitron Stainless Steel Slide 
• Frame Material: Polymer 
• Grip Material: Black Polymer with textured finish 
   

Detailed Features 

 
The P320's defining feature is its modular serialized fire control unit — the grip module, slide, and barrel can all be swapped independently, which means the pistol can be reconfigured for different sizes or calibers. This also makes the legal portion of the firearm the small FCU rather than the full frame, which has practical implications for those who want to own multiple configurations. 
 
The trigger has a consistent pull with a clean reset. Contrast sights use a three-dot configuration for quick acquisition. The Nitron finish on the stainless steel slide provides corrosion resistance. 
 

Usage Scenarios 

 
The full-size configuration works well for home defense, range use, and duty carry where concealability is secondary to capacity and sight radius. The 4.7-inch barrel gives a longer sight radius than compact variants, which aids accuracy at distance.

The P320 Full Size draws consistent positive feedback for its modular design — the ability to swap grip modules and reconfigure the pistol is a meaningful differentiator from standard polymer pistols, and owners discuss this frequently when explaining their choice.

Ergonomics get positive marks. The grip fits a wide range of hand sizes and the interchangeable modules mean buyers can dial in fit without buying a new pistol. Trigger quality is generally praised for its smooth pull and positive reset, though some shooters want a lighter pull weight.

Reliability across ammunition types is consistently mentioned as solid. The Nitron finish holds up well to regular use.

The main comparison discussion is against Glock and M&P. Most who chose the P320 cite the modular design and ergonomics as the deciding factors. Price is noted as higher than the Glock, and most buyers consider it justified given the feature set.