If you have a hard time getting certain things, just about any round designed for hunting will likely also work well for shooting humans, since the design parameters for both overlap a lot. Self defense rounds and deer hunting rounds are both about killing creatures that weigh around 150 to 300 pounds, after all.
Try to look for anything with a bonded softpoint bullet. Speer Gold Dots are great, if you can get those.
This is a bit off topic, but just in case nobody has mentioned this, get a flashlight on the rifle. It's very important to know exactly what you're pointing your gun at before you make the decision to shoot. There are plenty of flashlights and mounts designed to be attached to AR15s. But even if you can't get anything like that, a flashlight from the hardware store duct taped to the rifle is better than not having a flashlight on it at all. Even if it isn't ergonomic, flimsy, and looks stupid, I think being able to identify exactly what you're looking at before deciding to shoot is really important.