I used both cartridges for hunting, especially the cartridge 300 Win Mag in the seventies and eighties. I only used the cartridge 7mm Rem Mag intermittently and shot very few game with it.

At the moment I still own a rifle caliber 7mm Rem Mag, not because I am enthusiastic about this cartridge, but because of the weapon, a Lloyd rifle that happened to be available in this caliber.

I cannot say that there are big differences in the effectiveness of this cartridges, assuming the same type of bullet. At the end, one come to the same conclusion as the author, that heavier bullets can be used with the cartridge 300 Win Mag, but I have no experience with that. From the 1990s onwards, I preferred for hunting medium to heavy game bigger calibers and then used heavier bullets.