I think the 9mm was designed for 112-115gr bullets? Does this explain why pretty much all range ammo is 115gr? In other calibers range ammo is usually also the weight the original cartridge was designed for (180gr for .40S&W, 230gr for .45ACP, etc). I've seen some people recommend practicing with the same bullet weight as what you carry. That's hard to do if you carry 147gr 9mm.