The Genesis Arms GEN-12 18" Upper Receiver 12 Gauge is a purpose-built AR-style shotgun upper engineered to mate with DPMS GEN1 pattern .308 lowers. Using a short recoil system instead of a gas tube or piston, it delivers reliable cycling with a wide range of 12 gauge loads while maintaining a clean, streamlined profile with a full-length top rail and ventilated handguard.

This upper receiver is ideal for shooters building a versatile 12 gauge platform for range use, training, or hunting. It is designed to feed both 2 ¾" and 3" shells on a standard short DPMS .308 buffer and spring, with the option to tune recoil characteristics via buffer weights and springs. Genesis Arms’ focus on dimensional accuracy and functional compatibility gives builders a solid foundation for a dependable shotgun setup backed by the manufacturer’s reputation for thoughtful engineering and innovation.

• Manufacturer: Genesis Arms
• Model: GEN-12 18" Upper Receiver 12 Gauge
• Caliber: 12 Gauge
• Action: Short Recoil Operated Upper Receiver (No Gas System)
• Barrel Length: 18"
• Compatible Lowers: DPMS GEN1 .308 Pattern Lowers
• Shell Compatibility: 2 ¾" And 3" 12 Gauge Shells