A CMP GSM Clinic will get you to 200 yards. The principal is the same, except for the effects of wind and other environmental concerns.
Contact your state Rifle and Pistol Assn. (via google). Most have high power events and clinics for the same, that will get you to 600. Maybe 1000 yards.
Also might want to see about their F-Class events.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071