I'm confused Mas. The FBI is going back to 9mm from 40 S&W because advances in 9mm ammo, among other things. Recoil being one also. But I'm sure there have been just as many advances with 40 and 45. As far as recoil, my gen3,, 23 shoots about the same with 40 or 9mm+P in the conversion barrel. So to me a 23 with 40 or a 19 with +P is a wash for recoil. Don't know what ammo the FBI carries or qualifies with, but if its +P have they reduced recoil all that much?