I'm building my first AR (5.56, 16" mid length gas system, if that matters) and my question is which ammo should I use and which ammo should I stay away from? Is it true that each gun will have ammo that feeds properly and some that the gun just doesn't like? Which ammo is good? Which ammo is bad? And what makes it good or bad? Which ammo is clean and which ammo is dirty? ....sorry, I'm a total n00b. I'm learning everything from YouTube and this forum. I have no family or friends to teach me, so I'm depending on you guys...thanks in advance!