As many have said, either will work great if you find a good ammo match for the rifle. Just to make it a bit more concrete, I was looking for a specific ballistic comparison. For one example, I was looking at how Nosler loads these two cartridges. According to what they say, for whatever that is worth, in the TG line of ammo, they load them like this with both zeroed at 200 yds:
7mm RM - 168gr ABLR: Muzzle: 2,880 fps. 500 yds: 2,163 fps; -38.8” drop.
.300 WM - 190gr ABLR: Muzzle: 2,870 fps. 500 yds: 2,135 fps; -39.4” drop.
Almost identical except for the 22gr/13% heavier bullet out of the .300. Probably not going to make a difference in 99.9% of circumstances.
Of course, there are scores of other combinations. But I think that example illustrates how similar they are. The .300 can push a 13% heavier bullet at about the same speed as a 7mm. I have owned a .300 WM for 33 years. I painted houses when I was 19 and in school so that I could afford to buy the rifle I wanted—a Rem. 700 BDL in .300 WM. I still have it. I also have a 7mm Wby. I can’t tell the difference in performance of the two. I’m offering either of them to my 16-yr-old son to move up to from his .243 he used for years. He’s still thinking it over, but he seems to prefer the 7mm Wby.
If I had the choice to use a 7mm RM or 300 WM on any N. American hunt, and had accurate good loads for both, I might actually flip a coin. The only exception might be a brown bear hunt, for which I might prefer the 300 WM because you can load it with 200+gr bullets. But, in reality, a 175gr 7mm probably would do materially the same in almost all circumstances with the same shot placement. But that would be one hunt where I personally would choose the .300 WM.
As to recoil, I wouldn’t worry about either. Do two things when at the range: (1) put a removable bipod on the rifle; and (2) wear one of those leather, padded shoulder shooting pads. You never will have the slightest bruising, and the weight and padding will make any rifle much more comfortable to shoot. Take the bipod off for field use if you want. You will not notice the recoil in the field.
My dad, back when he was in his 40s, shot my 300 WM without doing those two things. He remembered that for decades, and said he said that he NEVER wanted to shoot that thing again. 11 years ago, then in his late-60s, I lent him that same rifle with full loads for an Alaskan bear hunt we were going on together. He did the two things I described above. He said he had no discomfort at all; and he got 1/2” groups at 100 yds. He said he couldn’t believe how much of a difference doing those two made. When I do those two things, I can shoot my .340 Wby at the range all day long without any discomfort.
Just my $0.02.
