I can't put down the 6/284, but I thought that I would give you an eye full on the 243 AI which was my windy day rifle on dog towns.
I shot 27"-30" Hart barrels with a minimum spec SAAMI reamer with zero freebore. Using a Remington 7/08 case neck downed and neck turned, 48.5g of Win 760 with a 70g Bullet got from 3850-4030 depending on the barrel length and choice of a CCI-250 primer or a Win Mag primer. Accuracy in all barrels were between .250-.300 at 100 yards.
Fireforming load was 47.0-47.5g of Win 760 with the CCI-250 at 3700-3750 fps.
Accuracy with the 85's was great at 3550 (max velocity with accuracy), but with greater bearing surface, the copper fouling was exponentially increased; since long shot strings inbetween cleanings were the norm, the lighter faster bullets performed the best on 150 rounds shot strings.
I had a friend that shot a 6/284. I do believe that the 6/284 will deliver higher velocities with the heavier bullets.
I had a 25/284, but traded it off because the round is just too long for a short action. As soon as you start jumping your bullets very far, accuracy suffers (especially if you are shooting a VLD bullet that may love jamming the lands). The 6/284 is much better suited on a long action if you ever intend to use the magazine.