What is the best all-around factory load for a Barret M82a1 for ranges out to about 2000yds?

You might have to try a few different places that make ammo and see how good their stuff works in your rifle. Do you want match or plinking ammo?

For match stuff try TTI Armory, Thunderbird Cartridge Co., AAA Ammunition, The Hunting Shack and Arizona Ammunition.

For plinking stuff try Watson's Weapons, Ammoman (limited time), Aim Surplus, Ammunition Store, Pat's Reloading, and High Tech Ammo. There are more and some of the places that sell match ammo also sell plinking stuff. Search the board also for other places and links.