Ive owned a 7mm mag for some 16 years now in a winchester model 70 classic, a near identical brother to the mauser(minor differences). Prolly the main thing you want to be sure, is that the rifle will feed your ammo reliably. If not, some minor tweaking may need to be done by a gunsmith. Majority are fine though. Have you shot it yet? I wouldn't worry with a brake yet, unless you are intolerant to the recoil. In my opinion, the rifle scope is too powerful, I would be thinking 4-14x, or 3-10x, or thereabouts. Sling is a good thing, bipod, if you can use it, go for it, otherwise its deadweight. I personally use 160gr as my all purpose weight, but thats for deer/elk. 150gr would probably be great for sheep, but I'd want 160 or the 175gr for moose. My preferred bullet is the Nosler Partition, but there are alot of good bullets made for the 7mm mags. Others will chime in with their thoughts, so you can have more points of view.