I rarely get a shot off at over 250 but would like something that has the capability to do so if necessary. Also I want something that is simple and reliable to use, Im not a tinkerer and dont like to have to coerce my weapons to be reliable. I want to pull the trigger, have the gun go BANG and a hole appear where I pointed it, again and again.

I'm very happy with my Armalite AR-10.

Contact Steve at ADCO firearms. He does an upgrade of the AR-10 that yields a tack driver.

I think , it all depends on the size of the target at 500 yards. If it is a 12x12 target a regular old AR-10A4 will hit it no problem 9 times out of 10. If you want better than 1 MOA acurracy, I would consider the AR-10T, but you might be able to get there with just a trigger job and free floating an AR-10A4.

I have just a regular AR-10A4 but free floated barrel which rarely misses a 12x12 steel plate at 600 yards, what would really get it more acurrate would be if I could get a better trigger and if I reload for it. But I only reload for my accuracy international or other bolt guns.

well i am a big fan of the ar10, but i am sure a dpms lr308 will serve you well, just keep in mind that every weapon to include the Knights mk11 may develop a problem from time to time, you really have to think about the company that supports your weapon, Armalite has a great life time warrenty, dpms has a year,