The Winchester SX4 20 gauge 28 in synthetic semi-auto shotgun is a gas-operated field gun engineered to cycle everything from light target loads to heavy 3-inch magnums without complaint. The Active Valve gas system adjusts pressure automatically, so you get reliable ejection and reduced felt recoil shot after shot. The 28-inch back-bored barrel with Invector-Plus choke tubes delivers consistent patterns and fast target acquisition via the TruGlo fiber optic front sight. This is a modern workhorse for hunters and clay shooters who demand low maintenance and high uptime.
| Manufacturer | Winchester |
|---|---|
| Model | SX4 |
| Material | Synthetic stock with textured grip panels |
| Compatibility | 20 gauge shells up to 3-inch |
| Finish | Matte black synthetic stock and metal finish |
| Weight | 6.25 lbs (per manufacturer specs) |
| Condition | New |
Key Features
- Active Valve Gas System — self-regulating piston cycles light 2.75-inch target loads and heavy 3-inch magnums without manual adjustment. The valve bleeds off excess gas for heavy loads and seals tight for light ones, so you get consistent ejection every time.
- Back-Bored Barrel with Invector-Plus Chokes — reduces shot deformation and felt recoil while improving pattern density. The 28-inch barrel with vent rib provides a smooth swing and clear sight plane for crossing targets.
- TruGlo Fiber Optic Front Sight — high-visibility red fiber optic post grabs light even in low-light field conditions. No batteries, no electronics, just a bright aiming point that works in dawn and dusk.
- Inflex Technology Recoil Pad — compressible pad reduces perceived recoil by up to 54% compared to standard pads, per Winchester testing. The textured synthetic stock with grip panels keeps your hands secure in wet or gloved conditions.
- Matte Black Finish — non-reflective surface reduces glare and resists corrosion from rain, snow, and saltwater. The synthetic stock won’t swell or crack like wood in humid environments.
Who It’s For
This is for the tech-savvy shooter who wants a gas-operated semi-auto that runs clean and cycles fast. Early adopters who appreciate self-regulating gas systems and low-maintenance synthetic stocks will feel right at home. It’s built for upland bird hunters, waterfowlers, and clay shooters who shoot a mix of loads and want one gun that does it all without constant cleaning.
Pros and Cons
- Pro: Active Valve gas system cycles 2.75-inch target loads reliably without needing to switch settings.
- Pro: At 6.25 lbs, it’s light enough for all-day carry in the field.
- Pro: Invector-Plus choke system gives you a wide range of constrictions for different game and clay disciplines.
- Con: The synthetic stock doesn’t offer the same aesthetic warmth as walnut — but it’s more durable and weather-resistant.
| Feature | Winchester SX4 20 Gauge | Benelli M2 20 Gauge | Remington V3 20 Gauge |
|---|---|---|---|
| Gas System | Self-regulating Active Valve | Inertia-driven | VersaPort self-regulating |
| Weight | 6.25 lbs | 5.8 lbs | 6.5 lbs |
| Choke System | Invector-Plus | Crio | Rem Choke |
| Stock Material | Synthetic with textured grip | Synthetic | Synthetic |
| Price | $967.64 | $1,499 | $999 |
| Recoil Reduction | Inflex Tech pad + gas system | Inertia + comb pad | Shock reduction system |
FAQ
Does this gun cycle light target loads reliably?
Yes. The Active Valve gas system adjusts to light 2.75-inch loads automatically. Many shooters report 100% reliability with 1-ounce target loads out of the box.
What choke tubes come with the Winchester SX4 20 gauge?
It includes three Invector-Plus chokes: Full, Modified, and Improved Cylinder. Extra chokes are available from Winchester and aftermarket brands.
Is the stock adjustable for length of pull or drop?
No, the synthetic stock is fixed. But the Inflex recoil pad can be swapped for aftermarket spacers or a different pad to adjust LOP slightly.
How does the gas system affect cleaning frequency?
Less than you’d think. The Active Valve vents excess gas through the fore-end, keeping the action cleaner. Field strips in under 60 seconds without tools.
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Last updated: April 2026
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