I had fgotten one of these brakes to put on a light weight 7mm Dakota but that project has benn put on hold so i put it on a new 300RUM. The gun has a #6 3groove Pac-Nor Super match barrel 1-10 twist thats finished at 28" the action is a Rem 700 that was a 300RUM to start with. The gun wheres a Hightech specialties light weight stock and scope and all the gun weighs a little over 10.5lbs. I shot the gun with the Cooley brake then with a Vias then without any brake. The Cooley brake worked the best and was the loudest the recoil was around that of a mid weight 270 or 25-06 the Vias brake had a bit more kick but a little less muzzel blast.Recoil ,maybe like a rem 700BDL in 30-06 with 165gr bullets without the brake is total nonsence !! it hurt !! I was going to try it against a Holland but I would have had to re-thread the Holland and index it to this barrel. The final load with this gun is a moly coated 180gr Accubond seated over 95grs ov VV-165 the velocity is right at the 3500fps mark and accuracy is almost .5" I want to try the 200gr accubonds soon as well. The purpose of this rig is for my dad to make long shots accross cutovers , powerlines and bean fields without having to do so much range adjustments.Max range is 700yds He loves it , not real crazy about the extra noise but says he can get used to wearing the ear plugs. All in All , for $90 the Bennie Coolie brake works and looks good , I seriously doubt that its any louder than the Holland.