Folks, I have a 2000 P99 9mm. I shot it when I bought it, in 2000, and have recently become interested in shooting it again! Upon cleaning the gun to get ready to shoot, I find that I have a silver recoil spring in the gun and a spare brown recoil spring! I seem to remember that Walther sent me the brown recoil spring along with a nice letter thanking me for my purchase and pointing out that the gun was designed for 124 gr hot EURO ammo, not 115 gr less hot American ammo! I believe their instructions were to use the original silver recoil spring for 124gr EURO ammo and the brown spring for 115gr American ammo. Can anyone verify that the silver spring is for heavier bullets and the brown spring for lighter? Is it necessary to change spring to shoot the 115gr bullets?