hey guys, so i recently bought my first ar15 an Olympic arms, And my goal for it is to make it into somewhat of a drm set up. and since this is my first gun i have no clue on how a few parts work and operate like the gas tubes and such. At the moment im trying to find a barrel and i have had my eye on the white oak armament 18 inch that can shoot 5.56 as well as .223. My goal with the gun is to be able to hit 500 - 700 yards. I have no idea how the gas systems work for the gun and im worried if i get a new barrel ill run into a lot of issues with cycling another round. If you guys have any tips for a first time owner id gladly appreciate it. or what kinda of ammo would serve best. I know since what i want to do with the gun i would have been better off building one. I have no idea if olympic arms is a good manufacture of guns. Things i still need is a barrel a decent scope a better stock and a bi pod If you guys have any cheap yet solid ones id love to hear about it. Thank you for your time.