The FN SCAR 20S is a semi-automatic rifle chambered in .308 Win / 7.62mm NATO with a 20-inch barrel, 10-round capacity, and an adjustable/folding stock. Overall length adjusts between 40.6 and 42.5 inches. Weight is 11.2 lbs. 
 

Key Specifications 

• Caliber: .308 WIN / 7.62MM NATO 
• Action: Semi-Automatic 
• Barrel Length: 20 inches 
• Capacity: 10 rounds 
• Weight: 11.2 lbs (179.2 oz) 
• Overall Length: Adjustable between 40.6 inches to 42.5 inches 
   

Detailed Features 

 
The short-stroke gas piston system keeps combustion gases out of the receiver, which reduces fouling on the bolt carrier compared to direct-impingement designs. The Geissele Super SCAR trigger is a two-stage match unit with a pull weight of approximately 3.5 to 4.5 lbs—a significant improvement over the standard SCAR trigger. Ambidextrous safety and magazine release serve both left- and right-handed shooters. 
 
The adjustable and folding stock makes the platform manageable in confined spaces and allows length-of-pull customization. At 11.2 lbs the rifle is heavy, which is partly a function of the piston system and heavier .308 components.

The FN SCAR 20S in .308 generates strong appreciation for build quality, accuracy, and the Geissele trigger. Owners doing precision work at long range frequently report tight groups and reliable function, and the short-stroke piston system's reduced fouling translates to fewer cleaning intervals noted in owner feedback.

The adjustable and folding stock is a practical feature that gets positive mentions. Modularity is appreciated by owners who want to run suppressors, optics, or bipods—the platform accommodates them well.

Weight (11.2 lbs before optic) is the most common criticism. For a designated marksman role at a fixed position it's workable; for a carbine used dynamically it's noticeable. Price is the second most common friction—the SCAR 20S sits at the premium end of the semi-auto .308 market, and some buyers feel comparable accuracy is achievable with less expensive platforms. Magazine availability and pricing draw occasional complaints, particularly for buyers used to the lower cost of AR-10 or M14-pattern magazines.