One thing that doesn't get a lot of press is blast. Blast really makes recoil seem much worse than it actually is. A 300RUM with a 26" barrel has enough of it to really get your attention. A 30-378 seems like 10X more. Brakes make it even worse. Increasing barrel length is the best answer even though that decreases muzzle pressure and you lose some of the effectiveness of the brake. They also have high recoil speed. They kick hard and FAST, also lowering the comfort rate shooting the thing. You can change this somewhat with powder burn rate and bullet weight. Slowest powders have lower recoil speed, but usually more recoil since you are burning more of it. They also tend to have the most muzzle pressure, which adds to blast and the effectiveness of the brake. Lighter bullets have less recoil but faster recoil speed. You can use this as a basic guide to play around with your load and address what seems to bother you most. Make sure the stock fits you well. Consult a good gunfitter. Then you have to actually shoot the thing often enough to get past the rest. Big fast guns kick hard and fast, its not going away in a rifle that is light enough to carry all day unless you are one strong cookie. You can learn to shoot it very well, and the reward is the thing is an absolute hammer for a long ways out.