The Sig Sauer MCX-Spear 16B is a semi-automatic rifle chambered in .308 Win / 7.62x51mm NATO. The 16-inch barrel, two-position adjustable gas valve, curved match trigger, and six-position telescoping folding stock combine in a Coyote Tan anodized package weighing 9.2 lbs with 20+1 capacity. 
 

Key Specifications 

• Brand: Sig Sauer 
• Model: MCX-Spear 16B 
• Caliber: .308 Win / 7.62x51mm NATO 
• Action Type: Semi-Automatic 
• Barrel Length: 16 inches 
• Capacity: 20+1 rounds 
• Weight: 9.2 lbs (unloaded) 
• Finish: Anodized Coyote Tan 
   

Detailed Features 

 
The two-position adjustable gas valve lets you tune the rifle for standard or suppressed use, and for different ammunition loads. That flexibility matters for a .308 platform where load pressure varies significantly. The curved match trigger is a meaningful upgrade from standard mil-spec triggers — lighter break, cleaner reset. 
 
The M-Lok free-float handguard has a full-length Picatinny rail on top and attachment points along the sides and bottom for lights, grips, or other accessories without adding a bulky rail section. The six-position telescoping folding stock makes the rifle compact enough to transport in a case that would normally accommodate only shorter carbines. 
 
At 9.2 lbs, the MCX-Spear 16B is toward the heavier end of the .308 semi-auto category, but that weight helps manage recoil from the full-power cartridge.

The MCX-Spear .308 in Coyote Tan gets positive feedback for build quality, ergonomics, and the adjustable gas system. Owners who run suppressors particularly value the two-position gas valve. The match trigger draws favorable comments from shooters focused on precision work.

Weight is the most common point of contention — 9.2 lbs unloaded is on the heavy side for a 16-inch rifle, and some buyers compare it against lighter competing options. Price is the other consistent concern; the MCX-Spear sits at the top of the .308 semi-auto market, which leads to ongoing comparisons with platforms that cost less. Aftermarket support is growing but still trails standard AR-10 pattern rifles.