The Kel-Tec SU-16B is a semi-automatic rifle chambered in 5.56x45mm NATO / .223 Remington with a 16-inch barrel. It weighs 4.5 lbs and accepts standard AR-15 magazines. 
 

Key Specifications 

• Brand: Kel-Tec 
• Model: SU-16B 
• Caliber: 5.56x45mm NATO / .223 Remington 
• Barrel Length: 16 inches 
• Action Type: Semi-Automatic 
• Weight: 4.5 lbs (72 oz) 
• Overall Length: 35.9 inches 
• Capacity: 10+1 rounds (AR-15 magazine compatible) 
• Sights: Adjustable Iron / Optic Ready Rail 
• Safety Mechanism: Crossbolt safety 
   

Features 

At 4.5 lbs, the SU-16B is lighter than most AR-platform rifles of the same barrel length. The Zytel receiver and black synthetic stock keep weight down without adding much bulk. The barrel has a salt bath nitride finish for corrosion resistance. Adjustable iron sights are included, and the optic-ready rail lets you add a scope or red dot. The crossbolt safety is intuitive for right- or left-handed shooters. AR-15 magazine compatibility means ammunition and spare magazines are easy to source. 
 

Who It's For 

The SU-16B suits shooters who want a lightweight .223/5.56 rifle for recreational range use, small game hunting, or home defense. Its AR-15 magazine compatibility is a practical advantage. New shooters may find the light weight and mild recoil of the 5.56 round approachable, while experienced users get a compact, packable rifle.

SU-16B owners generally like the rifle for what it is: a lightweight, affordable .223/5.56 option that takes AR magazines.

The weight is the most commonly praised feature. At 4.5 lbs it's noticeably lighter than most rifles in the same caliber, which matters during long carry days or multi-position range sessions. The adjustable sights get consistent positive mentions, and AR-15 magazine compatibility is seen as a major practical advantage. Affordability relative to AR-platform rifles comes up often in favorable discussions.

Reliability gets more mixed treatment than in-class competitors. Some owners report occasional feeding or ejection issues, especially with certain ammunition or when the rifle is dirty. This is the most common criticism and shapes recommendations toward keeping the rifle clean and testing ammunition types before relying on it for anything critical.

Polymer construction divides opinion. Some owners accept it as a weight-saving tradeoff; others feel less confident about long-term durability compared to traditional aluminum or steel receivers. Ergonomics are generally decent but some shooters find the fit is better for some body types than others.