I try to go easy on my 40 S&W S2K with a can, as far as ammo energy is concerned. Right now I shoot Federal 165 gr hydro shok that has a value of 161,700 when you multiply bullet weight, 165gr, times fps (980) = 161,700. I have found some subsonic ammo that is 200gr bullet weight, with a fps of 800, which comes out to 160,000. Because the 200gr bullet is traveling at a slower speed, and giving a lower mass times velocity number, I would think that it should be less stressful on the gun. Am I right, or just full of waste matter? Thanks for your help. In the past, I have been told to stay away from the 180gr bullets, because they were said to be hard on the gun.