Your question is too general please try and be a more specific than long range.
what budget are you giving yourself?
What kind of long distance experience do you have?
what kind of gun you run (tell us what kind of barrel you have)?
what kind of ammo u use, that kind of targets you shoot?
and last but not least how far away you want to go?
Some of those scopes I mentioned earlier are well over $3000, but all can be considered some of the best glass money can buy.
Thanks for your help but you're right I should have been more specific on the budget.
My budget is $400 and like I said, its my first ar-15 and I like to get the most out of my guns and I have not yet have a preference in long range ammo.