9mm hitting as hard as .45 is a joke. Anybody who has ever shot an IDPA match can tell you this. Why? Because when the .45 bullets hit the steel poppers, they fall QUICKLY. When the 9s hit the poppers, they USUALLY fall. Shoot one on the edge or low with a 9mm, and it's often still standing. The sensitivity of the targets can be adjusted, but .45s easily outclass the 9s. Also, in IDPA, the CDP division is 8 shot .45s (mostly 1911s), and their ammo must meet a 165,000 power factor. Power factor is calculated the same as momentum--bullet (in grains) X velocity (fps). A fairly hot 9mm load is a 115 @ 1200 fps (show me a factory 124 @ 1250 and I'll pay for the ammo). Power factor = 138,000. A typical .45 is 230 @ 850, which comes up to 195,500. No comparison. Kinetic energy, on the other hand, SQUARES velocity, giving lighter, faster bullets a theoretical advantage. Velocity in fps (squared) X bullet weight in grains/450240. Who came up with the 450240? My guess is some guy who thought 9mms were the bomb. KE for above 9mm load = 367. KE for above .45 load = 369. So, KE says they are equal. Go shoot some steel knock-down targets, and you may disagree. I think KE is crap. Now I have to go clean my Glock 9mm--there's another match this weekend.