So, I've recently bought my first 9mm, and I'm looking for SD ammo. Heretofore, in my snubbie, I just got the same weight bullet (158 gr) as my range ammo in standard power hollow points. I didn't really put much thought into it, but I was brand new and just bought the same brand I was using for target ammo. I'm trying to actually put some thought into choosing SD ammo for the 9. I've looked through a couple of older posts, and there are several manufacturers to choose from based on INGOer recommendations (Speer Gold Dots, Federal HSTs, Hornady Critical Defense/Critical Duty, Winchester PDX1/Ranger-Ts, etc. I've also seen some stellar reviews for Underwood Extreme Defenders on YouTube.). My questions mainly have to do with the other choices: bullet weight, bullet profile, and power. I saw in this other posts that people were using 124 or 147 gr bullets. Why are the heavier bullets better? Is a standard hollow point best or a "filled" (for lack of a better description) hollow point like the Critical Duty, and why? What about the Underwood and Ruger ARX type or bullet? What are the pros/cons to standard vs +P vs +P+? Obviously, the +P is faster than standard and +P+ faster than everything, but why are these options necessary? Thanks for any input. I appreciate it!