I bought a couple of D-springs for use in a model 92D. I have read this spring has less tension and can be used in the PX4. The PX4 spring and the new D spring were the exact same size and when I squeezed the springs the D spring seems to have less tension. So I swapped out the spring. Its an easy change over. So, I stick a snap cap in and start clicking I felt that there was very little change. hhhmmm. I took the other new D spring and cut 2 coils off. Cleaned it up with a grinding wheel and buffer to make the surface flat and swapped out the spring with the new modified D spring. Started clicking again. Now I really felt a differance. A big differance. I then shot 50 rounds of Blazer 230 grain FMJ without a glitch. I fully expect to fire a few hundred rounds of FMJ and maybe 50 to a hundred of my personal protection ammo before I fully trust this weapon but what do you pro's think? I just a rookie and read stuff. Anyway, so far so good.