The Sig Sauer M400 DH3 is a semi-automatic rifle chambered in .223 Wylde, built specifically for 3-gun competition. A Timney Daniel Horner Signature 2-stage trigger, fluted stainless steel barrel, and three-chamber compensator are the headline components. 
 

Key Specifications 

• Model: M400 DH3 3-GUN 
• Caliber: .223 Wylde 
• Action: Semi-Auto 
• Barrel Length: 16 inches (406.4 mm) 
• Capacity: 30+1 rounds 
• Weight: 7 lbs (3.18 kg) 
• Overall Length: 34.5 inches 
• Twist Rate: 1:8" 
• Stock Description: DH3 Adjustable Stock 
• Safety Features: Ambidextrous Manual Safety 
• Muzzle Type: Three Chamber Compensator 
   

Detailed Features 

The .223 Wylde chamber accepts both .223 Remington and 5.56 NATO ammunition without the throat pressure concerns of running 5.56 in a .223 SAAMI chamber. The Timney Daniel Horner Signature trigger has an adjustable pull weight, which lets shooters tune the break to their preference for faster, more accurate rapid fire. The fluted 16-inch stainless barrel reduces weight without sacrificing rigidity and dissipates heat faster during extended shooting. The three-chamber compensator cuts muzzle rise noticeably on follow-up shots. The grey Cerakote finish is durable against field handling. 
 

Usage Scenarios 

• 3-gun competition: the compensator, adjustable trigger, and DH3 stock work together to support fast transitions and accurate split times. 
• Recreational range use: the .223 Wylde chamber is flexible with ammunition choices. 
• Home defense: capacity and controllability are adequate, though this platform is tuned for competition rather than a defensive role.

The M400 DH3 3-GUN in Grey draws mostly favorable feedback from competitors and recreational shooters who appreciate its competition-focused design. The .223 Wylde chamber is consistently called out as an advantage: it handles both .223 Remington and 5.56 NATO reliably, which reduces ammunition logistics for range sessions and matches.

Build quality gets high marks. The receiver construction and ergonomic layout hold up during extended shooting, and the adjustable stock accommodates different body types and shooting positions without tools.

Accuracy is a regular topic. Shooters report tight groupings at typical competition distances, and the adjustable Timney trigger gets credit for consistent break weight that translates to better split times.

The price is higher than non-competition AR platforms, and some buyers debate whether the competition-specific features justify the cost for casual range use. A few owners note that certain parts are harder to source or require specific tools for modification, which can limit DIY work compared to more common AR configurations.