I put the kit in a 12ga., but similar trigger system. I ended using the medium weight spring. I also adjusted the medium weight spring to the slightly stiffer side. After testing it using a snap cap in the gun, the light weight spring was to light for me... it didn't take much presser at all fire the gun. I was concerned that it would be to easy to fire the gun accidently, especially when wearing gloves. I did not try the heavy spring.
