Possum_56
Im not going to give specific load data, as I go for shot-to-shot consistency rather than max loads, but I will provide some general suggestions based on my experience.
First, I only shoot 160g bullets in my 7mm Mag. Never felt the need to go lighter or heavier and the 160s have always performed. (A 160g is definitely more than needed for prairie dogs, coyotes, and antelope, but is great for mulies and elk. And I like to practice with my elk loads.)
Bullet selection has been the Speer Grand Slam for over 20 years. Ive launched these at 2850-2900fps and have consistently achieved pass-throughs ranges up to 350 yards, the longest Ive attempted on big game. In 20+ years Ive only recovered one Grand Slam and that one had taken out both shoulder joints of a 5x5 bull elk.
I tried Barnes XLCs on antelope, thinking if they worked I would use them on elk. At 300 yards I put two through the boiler room of a buck and both exited. Examining the wound channels later I couldnt tell if they had failed to expand or if they had expanded and the petals had just ripped off, but either way they failed to provide the quick and humane death I prefer the buck just stood there coughing up blood then laid down as if to sun himself. I ended up circling around and putting a third XLC through the heart some 20-30 minutes later from 100 yards. This one ended the bucks misery. I went back to Grand Slams for that years elk hunt.
Last year, after harvesting a buck mulie and a 6x6 bull elk with North Fork bonded bullets from my Marlin .45-70 the previous year, I switched to North Fork bonded bullets for the 7mm Mag and achieved the most consistent and accurate loads I have ever developed for that rifle. One 3-shot test group measured 0.266 center-to-center, less than one bullet diameter. North Fork bonded bullets are now my bullets of choice for the 7mm Mag, .300 Win Mag and .45-70.
For powder I have used IMR4831 until recently but use H1000 with my preferred North Fork loads. H4831SC gives me about 3000fps with the North Fork 160s but at a slight cost in accuracy (still under 1, though).
