The Winchester SX4 Waterfowl Hunter is a semi-automatic shotgun chambered in 20 GA with a 3" chamber, built around Winchester's self-adjusting active valve gas system. That system cycles various loads without manual tuning, which matters when conditions change between blinds and open water. 
 

Key Specifications 

• Brand: Winchester 
• Model Name: SX4 Waterfowl Hunter 
• Caliber: 20 GA 
• Chamber Length: 3" 
• Barrel Length: 26" 
• Overall Length: 47" 
• Weight: 6 lbs. 10 oz. 
• Capacity: 4+1 rounds (2 3/4" shells) 
• Sights: Fiber Optic Front 
• Finish Color/Pattern: Realtree Max-7 (Natural Camouflage) 
• Condition: New in Box 
   

Detailed Features 

• Rounded Close Radius Grip with Textured Surfaces: Provides a secure hold for precise control, particularly useful in wet conditions. 
   
• Back-Bored Technology: Increases bore diameter to reduce recoil and improve shot speed. 
   
• Self-Adjusting Active Valve System: Handles a wide range of load types without adjustments between sessions. 
   
• Drop-Out Trigger Group: Removes for cleaning and maintenance without tools. 
   
• Larger Bolt Handle: Easier to rack under cold or gloved hands. 
   
• Reversible Safety Button: Accommodates left- or right-handed shooters.

Users running the SX4 Gen 4 Waterfowl in 20 GA generally appreciate the lightweight build for long hunts, and the 20-gauge chambering keeps recoil manageable for fast follow-up shots. The Realtree Max-7 pattern gets good marks for blending into marshes and flooded timber.

The gas system cycles consistently across different loads according to most owners, and shot pattern feedback is positive across typical hunting ranges. A few users mention an initial break-in period where occasional jams occurred, but those generally resolved after the first few boxes. Some see the price as a bit high relative to other pump options, though most who've shot it feel the semi-auto gas action justifies the difference.