I have a Heckler and Koch full size USP .40S&W that's about 15 years old. According to the serial number, I think it was made the first year of production. Anyway, since it is getting pretty old, I decided it was time to possibly replace the springs. I bought two mag springs, a recoil spring (which came with a new extra power firing pin spring). One of the mag springs I bought directly from HK. The other mag spring and the recoil spring and firing pin spring from Wolff. I was a little uncomfortable buying aftermarket springs, but the price was right and to be honest HK was out of recoil springs. So I went with Wolff. My question is are Wolff gun springs any good? I've installed them and I've got to be honest, they're super stiff! There were upgraded heavier springs available, but I just bought the factory powered ones except for the mag spring which was +10%. The slide now I can barely pull back! I wonder if it's just like having a new gun now where you have to break it in a bit? If anyone who has experience with Wolff can share their thoughts, I'd greatly apprecaite it. I'm thinking it's just a case of my gun needed new springs more than I though!