Winchester SX4 semi-auto 20-bore

We tested the 12-bore SX4 last year and were very impressed by its fast-cycling action and superb handling. Now the company has introduced a new 20-bore version of the semi-auto with a few improvements.

First and foremost the gas-operated mechanism includes an active valve that vents gasses both upwards and forwards from the Quadra vent ports in the fore-end when using heavy loads such as magnum cartridges. This also regulates bolt speed.

The advantage of a gas-operated gun is that it is not cartridge fussy and will cycle