First off let me give you guys some context on my question so you can judge it accordingly. I just bought my first firearm about a month ago (Sig P226 9MM) and know very little about pretty much everything. I've been reading this forum for a while and all of the knowledgeable folks are great and pretty entertaining as well! Now to the question. Go easy... I'm a noob! I see lots of references to SD ammo vs range ammo. I understand that SD ammo is designed to inflict more damage and deliver greater stopping power as opposed to range ammo which is more for, well..... the range. I buy and shoot the Walmart Federal 9MM rounds since they're the cheapest option. I don't have any other ammo on hand in my house. I'm not comfortable enough with my gun to say it's really a SD option at this point. I'm continuing to work on it and will get there eventually. But.... if I were to be put in a situation where I could get to my firearm and use it for SD what would I be giving up if I were to engage a bad guy using good old Federal 9MM? I know that accuracy is a major component of this question as well so let's assume that I could shoot what I was aiming for and take that out of the discussion. I realize range ammo would be better than nothing, but how much of an advantage would I be giving up if I didn't use ammo that was better designed for the job?