I'm not trying to knock what you are doing at all, and the fact you can shoot past 300 yards and hit what you are aiming at is awesome when most gun owners, specifically AR owners couldn't hit the broad side of a bard, much less understand a proper zero on their guns.
But may I suggest you take a step back?
When would you ever realistically take a standing off hand shot on a target, other than the broad side of a barn at 600 yards?
The 5.56/.223 round wasn't even designed for that sort of thing, as far as being a practical man stopper at 600 yards.
What competition stresses shooting your rifle out of the scope of the capabilities?
What sort of optic are you running that is realistically going to allow you to shoot out to 600 yards, but also beable to make those fast close in shots that 3 gun, and 2 gun has?
Even a 1-8x optic is a pretty long shot on a medium to small piece of steel at 600 yards.
I ask not to be a smart ass, mostly because I'm curious. 600 yards is a long way from standing.