ProMag® Sig Sauer® P320™ 9mm 21-Round Extended Magazine – Heat-Treated Blued Steel Body – Flat Dark Earth (FDE) Polymer Baseplate – Made in the USA – SIG-A20-FDE
Product Description
The ProMag® Sig Sauer® P320™ 9mm 21-Round Extended Magazine (SIG-A20-FDE) represents a highly reliable, high-capacity feeding logistic solution, tactical sidearm optimization, and value-driven training enhancement, proudly manufactured in the USA. Purpose-built to provide seamless compatibility with your modular Sig Sauer P320 series handgun, this extended 21-round aftermarket variant successfully eliminates the financial burden of stocking premium duty magazines without cutting corners on mechanical execution. While traditional factory extended options command steep luxury markups, ProMag delivers a rugged steel-bodied alternative engineered to handle the severe stress of dynamic range sessions, high-volume action shooting matches, and secondary weapon staging loops.
The core structural frame of this 21-round performance module is precision-formed from high-grade, heat-treated high carbon steel. To guarantee absolute durability and structural resistance against crushing or accidental range drops, the seam is continuously TIG-welded and smooth-ground to follow strict modular magwell tolerances. The steel chassis is finished in a traditional corrosion-resistant blue steel/black oxide armor treatment, creating a low-friction surface that guarantees crisp, free-falling magazine releases during high-speed combat reload drills. To match the aesthetics of modern military issue sidearms like the M17 and M18, the magazine features an extended Flat Dark Earth (FDE) polymer endplate that cleanly extends past compact, carry, or full-sized grip frames, granting you added real estate for recoil containment control.
The true functional success of this American-made ammunition engine lies within its robust internal components and strict compliance layout. The inner track is driven by a premium, precision-wound spring formed from heat-treated chrome silicon wire. This state-of-the-art metallurgical selection ensures a high resistance to spring memory or fatigue, maintaining uniform upward pressure even when staged at full capacity for extended tracking timelines. Working in synchronization with a low-drag, injection-molded polymer follower, cartridges track cleanly without nose-diving or tilt jams. Backed by ProMag’s ironclad lifetime factory guarantee against manufacturer defects, this 0.28-pound high-capacity option yields absolute administrative and feeding uniformity across your defensive ecosystem.
Includes: (1) Authentic ProMag Sig Sauer P320 21-Round 9mm Steel Extended Magazine Assembly (Blued Steel Shell, High-Tensile Chrome Silicon Spring, Low-Drag Follower, Flat Dark Earth Polymer Baseplate Insert), Packed in Original Factory Sealed Retail Branded Hanging Card Presentation Packaging.
*Administrative Calibration & Jurisdictional Safety Guidance: The ProMag SIG-A20-FDE is designed exclusively for Sig Sauer P320, P320-M17, P320-M18, and P250 series handguns chambered natively in 9x19mm Parabellum; it will not properly cycle or seat inside older P226/P229 platforms or select fire caliber variants (.40 S&W/.357 Sig). **CAPACITY COMPLIANCE WARNING:** This extended magazine holds a 21-round payload footprint and cannot be legal for purchase, distribution, or transport within restrictive states with strict 10-round or 15-round limits (including California, Illinois, New York, New Jersey, and Massachusetts). Prior to conducting tactical reload practice or manual frame strips, always verify your sidearm chamber is entirely clear, isolated from live ammo tracks, and safe on your tracking bench.
Key Features
- Extended 21-Round Firepower Deck: Boosts your standard onboard carrying capacity to a robust 21-round layout, optimizing competition strings and decreasing down-time on the firing line.
- Heat-Treated Steel Shell: Formed from rugged heavy-gauge steel billet and TIG-welded to prevent body bowing, side-wall flexing, or feed-lip widening under maximum compression load lines.
- Flat Dark Earth Polymer Baseplate: High-impact technical polymer endplate provides a matching FDE tactical collar extension to complement coyote/tan military-style firearm furniture setups.
- Chrome Silicon Spring Resilience: Internal spring is precision-wound from heat-treated chrome silicon wire to fight back against spring set memory over extensive staging cycles.
- Injection-Molded Low-Drag Follower: Smooth anti-friction follower keeps the 9mm ammunition column aligned perfectly for stable, zero-tilt upward tracking into the weapon breach.
- Proudly Fabricated in the USA: Built from materials sourced entirely within domestic industrial networks and backed by an unyielding lifetime factory structural warranty baseline.
Product Specifications
- Brand: ProMag® Industries (Backed by ProMag's Authentic Lifetime Manufacturer Warranty Matrix)
- Product Line: Aftermarket High-Performance Tactical Handgun Ammunition Magazines
- Model Series Designation: Sig Sauer P320 9mm 21-Round Extended Magazine – FDE Edition
- SKU / MPN: SIG-A20-FDE (Alternative Industry Identifiers: MGPMSIG-A20-FDE / SIGA20FDE)
- Caliber System Optimization: 9x19mm Parabellum / 9mm Luger
- Ammunition Payload Capacity: 21 Rounds (Extended Frame Capacity Layout)
- Chassis Body Material: High-Carbon Heavy-Gauge Heat-Treated Carbon Steel
- Surface Protection Finishing: Anti-Friction Corrosion-Defeating Blue Steel / Black Oxide Coating
- Baseplate Interface Class: Extended High-Impact Injection-Molded Flat Dark Earth (FDE) Polymer Endplate
- Internal Spring Infrastructure: Precision Wound High-Tensile Heat-Treated Chrome Silicon Wire
- Follower Mechanical Profile: Low-Drag Anti-Tilt Injection-Molded Technical Polymer
- Firearm Host Compatibility: Sig Sauer P320, P320-M17, P320-M18, P320 X-Five, and P250 9mm Pistols
- Product Net Component Weight: ~4.48 oz (~0.28 lbs) - Rugged Extended Magazine Mass
- Total Packaging Shipping Mass: ~0.55 lbs (Enclosed Inside Protective Padded Retail Staging Sleeve)
- UPC Barcode Number: 708279016134
