So I was swapping around my unused PTR stock and my Hk SG1 stock(with heavy buffer) and I noticed something that seems a little off. The SG1 stock recoil spring seems to be lighter than the new PTR stock one. Atleast by a few pounds because its really noticeable when charging the weapon. Do these recoil springs go bad? And would a lighter tension spring have an adverse affect on a new roller lock weapon system, or recoil? If so how does one replace the spring.