Before relying on a red dot sight for distance shooting, find out the size of the actual red dot. If your shooting a 2 moa red dot sight at a target 200 yards away, you'll obscure your x-ring.
You will be able to hit your target if you're looking to be "combat" accurate, but not if you're target shooting for the bullseye.
"Your fear is 100% dependent on you for it's survival." - Steve Maraboli, Life, the Truth, and Being Free