Blackhats best bang for the buck, taken the course several times will take it again. Also shot at black water/xe and sig they are good too but more expensive
Re: Most accurate. 50 BMG on market.
Find a used Barrett 99 when you can shoot better than it trade up. Using xm33 (I am cheap $2.80) 12 x 12 plate is more than possible at 1K.
Re: Precision Rifle courses...
Took the precision rifle course at US Training Center old Blackwater Site in NC. Very good course shot out to a 1000 yards. They let me break out the M99 at the 1K range and showed me how to properly shoot it.