I have to admit to making a couple of layout errors.... the sear is the wrong way round but you'd work that out soon enough. The valve layout is slightly wrong. The part that looks like a spring guide or top hat should be fitted to the piercing pin side of the spring not the valve side. Also, there is a gasket/seal missing that seals between the CO2 capsule tube and the end of the valve. It was still in the pistol when I took the photo.
All the best,
Jimmie