I've been researchng balistics here on 9mm ammo for SD..Some say "go heavy" others say it doesn't really matter...I'm fine carrying a 9 as a primary carry...I keep my S&W MP45c as a nightstand gun as it's a bit much for me to carry...What is some good 9mm ammo that has adequate stopping power? Is 147gr compared to 124gr or 115gr JHP's make that much of a difference? My summer carry right now is a Kel Tec PF9 w/ Hornady 115gr critical defense...Someone please educate me on these matters...