I just bought a Bushmaster ar15, and took it out shooting a few days later to fire it for the first time, but I was soon to be disappointed as I had to get the top receiver polished, because it kept jamming. I'm still a AR fan as i knew this was just a fluke, and i will be shortly building one from the ground up. Any suggestions on parts to get (hand guards, receivers,trigger components) would be great, as I am new and don't know who makes the best parts for an AR.
You're going to have to be a bit more specific as to what type of failures your were experiencing, what type of rifle it is (i.e. barrel length, buffer type, etc), what kind of ammo you were using, what type of magazines you were using. These all factor into malfunctions.