So, I'm looking to stock up on a little ammo for my primary "SHTF" rifle, my Colt AR15. I buy most of my ammo from SG Ammo, cause they usually have what I'm looking for a shipping isn't too bad. My question is, what 556/223 should I buy? My rifle seems to shoot (maybe it's me) both 193 and 855, and a few different .223 rounds that I've tried, all the same, or very close. I'd like to stick with something affordable, but not down to Wolf. It's looking like I need to pick XM193 or XM855, and go from there. Are the green tips good for general use, training, and if it came to it, survival, or is the 193 better? How are the Battle Packs? Seems like a nice idea for storage...I see Prvi and IMI both have reasonably priced bulk ammo. What should I get?!