I installed a 15 pound recoil spring in my Beretta M9 but with Federal American Eagle 115 Grain FMJ I got one FTF. The gun closed on an empty chamber with more rounds in the mag. What is the real benefit of a stronger recoil spring? Is it worth it keeping it in the gun or should I keep the factory spring in there? Also I got 2 failures to ignite the primers with the same ammo but with Beretta's double action I was able to pull the trigger again and the rounds went off. I think the failure to ignite was due to the fact that I replaced the factory 20 pound hammer spring with 13 pound competition spring. The #13 spring made a huge improvement in the double action trigger pull. I did not have the same problems with other ammo I shot in the gun, which was WWB, Fiocci and CCI Gold Dots.