Hello, I was hoping to get some feedback on a good recoil spring weight for a .40 full-size p320. I recently purchased a full-size .40 slide from gunbroker and picked up a fat stainless guide rod so I could adjust the spring weight. I called Sig inquiring about the factory spring weight for the .40 and they said it was 20lb. so I played it safe and bought a 18.5lb 1911 spring. It works fine however I feel like I could go lower and would like the gun to shoot a bit flatter. A guy at a USPSA match last week said I could go to 15lb, but that seemed a bit low.