The M400-SDI X was designed to meet the highest standards of performance and reliability. From the rifle's full suite of ambidextrous controls to its proven mid-length gas system. Features fully Ambi Controls- safety, charging handle, bolt Catch & mag release; 2-Stage Matchlite Duo trigger; free floating M-LOK; mid-length direct impingement operating system and 6 position Magpul SL stock.
Brand Sig Sauer
Category Tactical Rifles
Series SDI-X
Model M400
Caliber 5.56 NATO
Gun Platform AR-Style
Operating System Direct Impingement
Stock Finish Group Black
Capacity 30+1
Stock Material Synthetic
Action Semi-Auto
Oal 33.25' - 36.50"
Hand Ambidextrous
Sights None
Barrel Finish Black
Barrel Material Chrome Moly Steel
Muzzle Sig Flash Hider-Compensator
Twist 1:7"
Receiver Description Picatinny Rail
Magazine Type AR-15
Grips Reduced Angle
Handguards M-LOK
Height 7.10"
Receiver Material Aluminum
Safety Lever
Thread Pattern 1 / 2"x28
Width 2.80"
Stock Description 6 Position Magpul SL
Barrel Description Threaded
Barrel Length 16"
Max Capacity 30
Receiver Finish Moss Green Cerakote
Trigger Sig Two-Stage Matchlite Duo
Weight 7 lbs
Stock Finish Black
Handguard Finish Moss Green
Caliber Dictionary
The Below Information Has Been Provided From Our Gun Caliber Dictionary And Is Meant For Informational Purposes Only. It Is Not Intended to Describe The Unique Specifications For This Ammunition.
The 5.56X45mm NATO cartridge was designed by James Sullivan, a member of Eugene Stoner's engineering team that developed both the M16 rifle and its original cartridge. The 5.56X45mm NATO was adopted by the U.S. military in 1964 and by NATO in 1980. With bullet diameter of .224-inch, the original M193 military cartridge used a 55-grain bullet at 3250 fps; the current M855A1 cartridge, developed by FN, uses a 62.5-grain bullet at 3020 fps, offering greater range and better penetration. The civilian version of the 5.56X45mm is 223 Remington; the cartridges are dimensionally identical but military chamber dimensions and specifications for military brass are different. It is considered safe to use 223 Remington ammo in a 5.56X45MM NATO chamber, but not a good idea to use 5.56X45mm ammo in a rifle specifically chambered for the 223 Remington. Although the stopping power of .22-caliber bullets remains controversial the 5.56X45mm has served well in now multiple generations of M16 rifles. — Craig Boddington
