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Sig Sauer P320 Series

The Ultimate Expression of Modern Handgun Modularity

As the foundational architecture for the U.S. Military's sidearm, the Sig Sauer P320 revolutionized handguns with its patented Fire Control Unit (FCU). By housing the serialized internal chassis separately, the P320 allows shooters to swap caliber, frame sizes, and slide lengths instantly to build a custom tool for duty, concealed carry, or competitive matches.

  • Serialized Fire Control Unit: The heart of the system—move the stainless steel FCU framework across entirely different grip modules and slide lengths in seconds.
  • Optic-Ready Flexibility: Factory slides come strategically machined with top cuts to accept modern red-dot optic footprints without custom gunsmith work.
  • Smooth Striker Performance: Features a crisp, clean-breaking factory trigger pull with a highly positive, tactile reset for predictable follow-up shots.
  • Elite Variant Ecosystem: Scales effortlessly from duty-ready polymer frames up to weighted competition platforms and classic metal-alloy configurations.

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Sig Sauer P320 Variant Specification Matrix

P320 Variant Grip Module Material Typical Barrel Length Standard Capacity Controls / Aesthetics Core Application
P320 Compact / Carry Standard Polymer 3.6 in or 3.9 in 15 to 17 Rounds Sleek profile, concealable footprint Concealed Carry / Everyday Protection
P320 Full Size Standard Polymer 4.7 in 17 Rounds Maximum sight radius, standard duty controls Open Carry / Duty Sidearm / Home Defense
P320 XFIVE Legion TXG (Tungsten-Infused Polymer) 5.0 in (Bull Barrel) 17 to 21 Rounds Heavyweight frame, flared magwell, skeletonized trigger Competition Shooting / Low-Recoil Speed
P320 AXG Series Anodized Aluminum Alloy (Metal) 3.9 in 17 Rounds Interchangeable side grip panels, classic metal feel Premium Custom Build Enthusiasts
P320 M17 Coyote Tan Polymer 4.7 in 17 & 21 Rounds Ambidextrous manual safety, military markings U.S. Military Spec Service Clone
P320 M18 Coyote Tan Polymer 3.9 in 17 & 21 Rounds Ambidextrous manual safety, compact military configuration Tactical Carry / Military Service Clone

Sig Sauer P320 Frequently Asked Questions

Q: What is the Fire Control Unit (FCU) and how does it affect purchasing?
The Fire Control Unit (FCU) is the inner trigger mechanism chassis. Unlike standard handguns where the plastic frame is the restricted part, the stainless steel FCU is the only legally serialized component of the P320. This means you can order different grip frames and slide configurations directly to your doorstep, as long as you swap your single factory FCU into them.
Q: What is unique about the P320 Legion (TXG) grip modules?
The P320 XFIVE Legion utilizes a specialized TXG grip module engineered by infusing heavy tungsten powder directly into the polymer matrix. This yields a frame that looks and flexes like polymer but carries the weight of solid steel (increasing the overall build weight to over 43 ounces). This added mass dampens felt recoil and mitigates muzzle flip dramatically during rapid firing schedules.
Q: How do the P320 AXG versions differ from regular polymer P320s?
AXG stands for Alloy XSeries Grip. Instead of polymer, the AXG line features an aluminum alloy metal frame machined with interchangeable side grip panels (often utilizing premium G10 or hardwood). It delivers the crisp, rigid mechanical return and heirloom heft of a classic all-metal pistol while maintaining total compatibility with standard P320 striker slides.
Q: What are the main differences between the military M17 and M18 models?
Both firearms are commercial iterations of the U.S. Army's Modular Handgun System sidearms. The primary distinction comes down to length: the M17 features a full-size 4.7-inch barrel/slide assembly, while the M18 features a compact 3.9-inch barrel/slide assembly. Both utilize Coyote Tan styling and include ambidextrous manual frame safeties.
Q: Are P320 magazines cross-compatible across Compact and Full Size configurations?
Larger magazines work perfectly in shorter grips, but not vice-versa. A full-size 17-round or 21-round magazine will lock and feed cleanly inside a Compact grip frame (though it will extend out from the bottom). However, a short 15-round Compact magazine is physically too short to reach the locking catch inside a tall Full-Size grip module.
revolver barrel loading graphic

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