Just put the flat FSS in my 5" 9mm CORE, 4 lbs 1.6oz average over 10 trigger pulls. I'm extremely impressed. This is, however, the only pistol I will be putting this trigger in. My M&P9C has a performance center sear and I set aside my CORE's performance center sear to go into the 4.25" full size I plan on buying soon. I love the PC sear, perfect for a SD/HD type pistol, but the CORE's only purpose for me is putting extremely small ragged holes in paper.