There is only one recoil assembly for both 9mm and .40. They're identical, down to the part number. The P2000SK is the only modern HK gun that has this unique 2-part recoil assembly, if I am not mistaken. The majority of them have the plastic buffer over the spring, and the full-size USPs have the dual recoil springs.I might be mixing up my recoil springs on the USPc and the P2000sk. I'm away from home right now so I dont have them in front of me to compare but the parts site shows only one recoil spring for the P2000sk in all calibers and instead of a plastic bushing there is a second spring over the rod like you shown in your photo.