local trouble maker
Makes no sense to use underpowered loads for defensive training purposes....what happens if you actually have to use full power +P self defense ammo :dunno:
Nothing. As a personal experiment I threw a couple of hand full of full power SD loads in my box of IDPA ammo and mixed it in. I use a cardboard box that holds several hundred lose rounds. So when I was loading up my mags I didn't have a clue which bullet was which. The only difference I noticed was some were louder than the others. My opinion is practice and repetition are important than the power factor of your ammo.
Not to mention that the lighter ammo is going to be a lot easier on your joints. Do you want to be like jack and have to get the butler help you walk across the room? I don't have a butler. Who would open my beer?