This may or may not apply to what has been said here. I shoot a 356 originally chambered that way. Tried Varget the other day with the 200gr. RN, and felt it was a bit slow. I didn't really push it, but started with the min. dose for a 358, and worked up a couple of grains, and it showed little promise other than it was accurate. Significantly slower velocities than the following. H4198 and H322, 2520, are all superior in performance, and I am sure they are higher in pressure. These may not be the loads for a converted rifle. Shooting those bullets at 2400 plus is simply a toast to modern engineering. You better hit what you aim at, because it will red mist a rib cage at 100 yards with no problem. The 220 Speer may be a bit more appropriate if you want the bullet to penetrate a larger animal. I have a feeling this is pushing that bullet to its maximum effect.