The Shadow Screwgate is based on DMM's successful Shadow back with a couple of tweaks i.e. they extended the top bar to allow the locking version to have more room for knots and slings. Thus although it shares the same name as the Shadow straight and bent gate carabiners it has it's own tooling.
The barrel on the gate is machined from premium 7075 alloy to give it massive push-in strength. There is no current standard for this test, but at DMM, they don't build their carabiners to meet standards; they build their kit as well as they can, eliminate weaknesses and help push the standards forward.
The shadow has a keylock nose and is fully anodised for long term protection against the elements. The gate/barrel/nose intersection is designed and manufactured so that the barrel will not jam shut in the closed position if the carabiner is tightened under load.