I'm running with a #15 main spring. I did a Cajun Gun Works Pro Package installed by CGW, you can look up my post about it for more details. Long story short, after the Pro Package was installed by CGW, I had a few light strikes. I sent my P-01 back to Cajun after speaking with them and they double checked everything and returned it with a #15 lb main spring. Trigger pulls with the #13 MS were 7.9 and 3.7 with the #13. With the #15 they gauged it at DA - 7.12 and SA - 3.9. I've had zero issues.