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  • Everything you need to know about reloading
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      Reloading Dies
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M400 5.56 NATO SEMI-AUTO RIFLE W/ROMEO-MSRTM GEN II - M400 FORGE 5.56 16''BBL (1)10RD MAG BLK W/ROMEO-MSR GEN II

M400 5.56 NATO SEMI-AUTO RIFLE W/ROMEO-MSRTM GEN II – M400 FORGE 5.56 16”BBL (1)10RD MAG BLK W/ROMEO-MSR GEN II

Specifications

  • Cartridge: 5.56 x 45
  • Make: Sig Sauer
  • Barrel Length: 16''
  • Rear Sight: None
  • Length: NA
  • Weight: 6.8 lbs
  • Model: M400 Forge
  • Capacity: 10+1-Round
SIG SAUER M400 5.56 NATO SEMI-AUTO RIFLE W/ROMEO-MSRTM GEN II
 
The SIG SAUER M400 FORGE is a duty-ready AR-style rifle engineered for reliability, accuracy, and modern handling. Built around a 16” cold hammer forged barrel with a mid-length gas system, the M400 FORGE delivers smooth recoil impulse, extended barrel life, and consistent performance across a wide range of ammunition.
 
A premium TriggerTech 3.5-lb two-stage flat-blade duty trigger provides a crisp, predictable break ideal for both precision shooting and defensive applications. Combined with a 15” M-LOK handguard, ambidextrous controls, and a MAGPUL SL-K adjustable stock, the M400 FORGE offers a well-balanced, configurable platform ready for hard use at the range, on duty, or in competition.
 
FEATURES
  • 16” Cold Hammer Forged Barrel – Mid-length gas system for reliable cycling and reduced recoil
  • TriggerTech Two-Stage Duty Trigger – 3.5-lb pull with flat blade design
  • 15” Free-Float M-LOK Handguard – Full-length Picatinny rail for optics and accessories
  • Ambidextrous Charging Handle – Enhanced control for right- or left-handed shooters
  • MAGPUL SL-K Stock – Six-position adjustable stock for length-of-pull customization
  • Forged Alloy Receiver Set – Lightweight strength with anodized finish
SPECS
  • Caliber: 5.56 NATO
  • Barrel Length: 16
  • Barrel Twist: 1:7
  • Gas System: Mid-Length
  • Overall Length: 32.25 (collapsed) / 35.5 (extended)
  • Overall Width: 2.7
  • Weight (w/ magazine): 6.8 lb
  • Receiver Material: Alloy
  • Finish: Anodized
  • Trigger: TriggerTech 2-Stage Flat Blade, 3.5 lb
ROMEO-MSR GEN II RED DOT
 
The ROMEO-MSR Gen II is a rugged, lightweight red dot designed for fast target acquisition and dependable performance. Featuring a 2 MOA dot, long battery life, and a durable, waterproof housing, it provides a simple and effective optic solution for the M400 FORGE platform.
 
SPECS
  • Optic Type: Red Dot Sight
  • Magnification: 1x
  • Objective Lens: 20 mm
  • Reticle: 2 MOA Dot (Red)
  • Illumination Settings: 12 (10 Day / 2 NV)
  • Battery Type: CR2032
  • Battery Life: Up to 35,000 hours
  • Mount Height: Absolute Co-Witness
  • Water Resistance: IPX-7
  • Weight: 5.7 oz
Description

Original price was: $999.99.Current price is: $871.00.

SIG SAUER M400 5.56 NATO SEMI-AUTO RIFLE W/ROMEO-MSRTM GEN II
 
The SIG SAUER M400 FORGE is a duty-ready AR-style rifle engineered for reliability, accuracy, and modern handling. Built around a 16” cold hammer forged barrel with a mid-length gas system, the M400 FORGE delivers smooth recoil impulse, extended barrel life, and consistent performance across a wide range of ammunition.
 
A premium TriggerTech 3.5-lb two-stage flat-blade duty trigger provides a crisp, predictable break ideal for both precision shooting and defensive applications. Combined with a 15” M-LOK handguard, ambidextrous controls, and a MAGPUL SL-K adjustable stock, the M400 FORGE offers a well-balanced, configurable platform ready for hard use at the range, on duty, or in competition.
 
FEATURES
  • 16” Cold Hammer Forged Barrel – Mid-length gas system for reliable cycling and reduced recoil
  • TriggerTech Two-Stage Duty Trigger – 3.5-lb pull with flat blade design
  • 15” Free-Float M-LOK Handguard – Full-length Picatinny rail for optics and accessories
  • Ambidextrous Charging Handle – Enhanced control for right- or left-handed shooters
  • MAGPUL SL-K Stock – Six-position adjustable stock for length-of-pull customization
  • Forged Alloy Receiver Set – Lightweight strength with anodized finish
SPECS
  • Caliber: 5.56 NATO
  • Barrel Length: 16
  • Barrel Twist: 1:7
  • Gas System: Mid-Length
  • Overall Length: 32.25 (collapsed) / 35.5 (extended)
  • Overall Width: 2.7
  • Weight (w/ magazine): 6.8 lb
  • Receiver Material: Alloy
  • Finish: Anodized
  • Trigger: TriggerTech 2-Stage Flat Blade, 3.5 lb
ROMEO-MSR GEN II RED DOT
 
The ROMEO-MSR Gen II is a rugged, lightweight red dot designed for fast target acquisition and dependable performance. Featuring a 2 MOA dot, long battery life, and a durable, waterproof housing, it provides a simple and effective optic solution for the M400 FORGE platform.
 
SPECS
  • Optic Type: Red Dot Sight
  • Magnification: 1x
  • Objective Lens: 20 mm
  • Reticle: 2 MOA Dot (Red)
  • Illumination Settings: 12 (10 Day / 2 NV)
  • Battery Type: CR2032
  • Battery Life: Up to 35,000 hours
  • Mount Height: Absolute Co-Witness
  • Water Resistance: IPX-7
  • Weight: 5.7 oz

Out of stock

SKU 430118090 Category

Description

SIG SAUER M400 5.56 NATO SEMI-AUTO RIFLE W/ROMEO-MSRTM GEN II
 
The SIG SAUER M400 FORGE is a duty-ready AR-style rifle engineered for reliability, accuracy, and modern handling. Built around a 16” cold hammer forged barrel with a mid-length gas system, the M400 FORGE delivers smooth recoil impulse, extended barrel life, and consistent performance across a wide range of ammunition.
 
A premium TriggerTech 3.5-lb two-stage flat-blade duty trigger provides a crisp, predictable break ideal for both precision shooting and defensive applications. Combined with a 15” M-LOK handguard, ambidextrous controls, and a MAGPUL SL-K adjustable stock, the M400 FORGE offers a well-balanced, configurable platform ready for hard use at the range, on duty, or in competition.
 
FEATURES
  • 16” Cold Hammer Forged Barrel – Mid-length gas system for reliable cycling and reduced recoil
  • TriggerTech Two-Stage Duty Trigger – 3.5-lb pull with flat blade design
  • 15” Free-Float M-LOK Handguard – Full-length Picatinny rail for optics and accessories
  • Ambidextrous Charging Handle – Enhanced control for right- or left-handed shooters
  • MAGPUL SL-K Stock – Six-position adjustable stock for length-of-pull customization
  • Forged Alloy Receiver Set – Lightweight strength with anodized finish
SPECS
  • Caliber: 5.56 NATO
  • Barrel Length: 16
  • Barrel Twist: 1:7
  • Gas System: Mid-Length
  • Overall Length: 32.25 (collapsed) / 35.5 (extended)
  • Overall Width: 2.7
  • Weight (w/ magazine): 6.8 lb
  • Receiver Material: Alloy
  • Finish: Anodized
  • Trigger: TriggerTech 2-Stage Flat Blade, 3.5 lb
ROMEO-MSR GEN II RED DOT
 
The ROMEO-MSR Gen II is a rugged, lightweight red dot designed for fast target acquisition and dependable performance. Featuring a 2 MOA dot, long battery life, and a durable, waterproof housing, it provides a simple and effective optic solution for the M400 FORGE platform.
 
SPECS
  • Optic Type: Red Dot Sight
  • Magnification: 1x
  • Objective Lens: 20 mm
  • Reticle: 2 MOA Dot (Red)
  • Illumination Settings: 12 (10 Day / 2 NV)
  • Battery Type: CR2032
  • Battery Life: Up to 35,000 hours
  • Mount Height: Absolute Co-Witness
  • Water Resistance: IPX-7
  • Weight: 5.7 oz

Additional information

Weight 7.55 lbs
Make

Sig Sauer
Barrel Length

16''
Rear Sight

None
Length

NA
Weight

6.8 lbs
Model

M400 Forge
Capacity

10+1-Round
Magazine Included

1 x 10-Round
Magazine Type

Removable
Muzzle

Flash Hider
Front Sight

None
Cartridge

AKK_5.56 x 45
Stock Material

Polymer
Action Type

Semi-Auto
Finish

Black
Make/Model

Sig Sauer, M400 Forge

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Frequently Asked Questions

Are these brass cases and reloading components factory-new or once-fired? +

We stock both premium factory-new components and high-quality once-fired brass. Please check the specific product listing title and description carefully; once-fired brass is fully inspected, but we always recommend resizing and inspecting prior to priming and powder charging.

Will this case trimmer gauge or die set work with my progressive press setup? +

Our standard reloading dies and case length trimmer accessories utilize industry-standard threads (typically 7/8"-14) compatible with major single-stage, turret, and progressive presses like RCBS, Hornady, Lee Precision, and Dillon. Caliber-specific trim gauges must match your exact brass caliber.

Do you enforce shipping restrictions on powder, primers, or live ammunition? +

Yes. Non-hazardous reloading equipment (dies, case length trimmers, gauges, and unprimed brass) ships via standard ground carriers with no extra fees. Any orders containing smokeless powders or primers will incur standard federal HazMat handling fees and cannot be shipped via air transportation.

How can I track my shipment to ensure delivery safety? +

Precision reloading gear is valuable, so all orders are shipped with tracking enabled. As soon as your package is dispatched from our inventory warehouse, a tracking number will be emailed to you. You can monitor your shipment directly on our Track Order page using your unique Order ID.

Can I return precision measuring tools or die components if they don’t fit? +

We accept returns on unused, unaltered tools, case preparation equipment, and unopened component boxes within 30 days of item delivery. Due to safety and strict quality control on the reloading bench, we absolutely cannot accept returns on opened packs of primers, smokeless powder, or processed brass casings.

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