Im suprised the 6-44 hasntbeen mentioned. I shot one of these quite successfully in hunter class for a number of years. Theres a gentleman from NC has done very well with one at 600 and longer. The44mm case gives a 1/4" more capacity than the br and should give perhaps 100+fps over the br. Cases today can be made from some of the Lapua offerings, rather than the old days need to form from Rem URBR cases. A lot of practice sessions @ 275 yds reulted in 5 shot < 5/16" groups, this with 6X optics. Never had the option to shoot longern than 300 yds then, but would not have hesitated to shoot it w/heavy bullets, correct twist etc @ 1K. Good case middle capacity, proven accuracy. Just another suggestion.