My P10C, new out the box, had a 6 1/2 lb trigger pull that was extremely gritty. I found the problem, a bur on the frame where the trigger goes through. It rubbed on the trigger leaving a deep scratch. I smoothed out that bur, added a HBI trigger and things got a lot better. Now I have a smooth 4 lb trigger pull.
I used the original spring NOT the ones that came with the HBI trigger.