I have a Cooper model 22 6.5x284 and I'm shooting the Berger 130 VLD hunting bullet. Mine has the 9 twist and Berger recommends a 8 twist for the 140's so that's why I'm shooting the 130's. Started with the straight H4831 and never seen a need to try anything different. It will probably shoot better than I can. I just got my magnetospeed chronograph
in but haven't had a chance to test the load yet because of work. I need to be around 3000 fps so the velocity reticle in my nightforce will match up correctly. I started at 50 gr and worked my way up to 53 gr and thats as far as I've got. H4831 or H4350 would be a good place to start. Your going to love that Cooper!