The SanTan Tactical STT-15 Lite is a semi-automatic rifle chambered in 6mm ARC. At 6.9 lbs. with an 18-inch carbon fiber barrel, it's built light without sacrificing the barrel length needed for the 6mm ARC to perform well at distance. Black anodized finish throughout, 28-round capacity. 
 

Key Specifications 

• Caliber: 6MM ARC 
• Action: Semi-Automatic 
• Capacity: 28 Rounds 
• Barrel Length: 18 Inches 
• Weight: 6.9 lbs. 
• Finish: Black Anodized 
   

Features 

 
Carbon Fiber Barrel: Reduces weight and handles heat better than a standard steel barrel during sustained fire, which matters for accuracy over longer sessions. 
 
Single-Stage Match Trigger: Clean break with no notable creep — a real upgrade over mil-spec for anyone doing precision work. 
 
Adjustable Magpul CTR Stock: Length of pull adjusts to fit the shooter, which is useful when shooting in different gear or sharing the rifle. 
 
16" M-Lok Handguard: Plenty of rail space for lights, grips, or other attachments without adding much bulk. 
 
6mm ARC is a capable cartridge for both precision target work and hunting — flat trajectory, moderate recoil, and competitive at longer ranges where 5.56 starts to fade.

Owners of the STT-15 Lite in 6mm ARC generally like what SanTan Tactical delivered. The weight is a consistent talking point — 6.9 lbs. with an 18-inch barrel is genuinely light for a rifle at this configuration, and the carbon fiber barrel gets credit for that. The match trigger gets favorable mentions for its clean break. The 6mm ARC chambering draws interest from precision shooters and hunters who want better long-range ballistics than 5.56 on the same AR-15 platform.

The practical criticisms are worth noting: 6mm ARC ammunition is harder to find and costs more than 5.56 or .308, which adds up with regular range use. Some users also find aftermarket component selection narrower than for more common AR calibers, which can limit customization.

Price is mentioned occasionally as high relative to comparable ARs, though most who own one feel the build quality and weight savings justify it. Overall sentiment leans positive among shooters who specifically wanted a lightweight 6mm ARC build and understood what they were getting into.