"Why use cheap ammo...?" Because it's CHEAP!!! Crawling around on my hands and knees looking for used brass in the tall grass is not my idea of fun...and not all cheap ammo shoots like s**t. My SwissArms shoots the RUAG stuff great, but is not so hot with PMC or Wolff crap. My buddy's Mini-14 Target is not bad with anything, but shoots the old Winchester white box stuff within about 1/4-inch of my Swiss/RUAG. So his gun costs less than a third of what mine did, his ammo is like half the price, and the results are essentially the same.
I hate him.