Since "best" is so subjective, and everyone needs to find the rounds that work best in their gun, perhaps a better question should be, which rounds do not work well, or shouldn't be used. While I have shot a box of Winchester White Box 115gr FMJ, many people report problems feeding this ammo. There is variant of the Wolf ammo that most people don't like, and anything with steel cases should be avoided due to perceived wear and tear of the firing mechanism. I did have trouble with RJS 115gr FMJ keyholing, and I've shot a lot of Walmart Federal Champion fairly reliably, and a bunch of S&B 115 FMJ very reliably, and cheaply. As far as accuracy, the gun is far more accurate than I am from a normal standing stance, but I have heard hollow points are more accurate due to most of the weight being towards the back of the bullet, adding stability. As far as good HD or SD rounds, Hornady's Critical Defense, Speer Gold Dot, Winchester DPX1, are all good choices. So have fun, try a bunch of different ammo to find what your gun thinks is best.