One of my buddies has a ported .338 Win Mag.
He tells me the rifle hurts to shoot and can't believe that my .338 Win Mag is the pussycat that it is. Mine has a muzzle brake. I'd call that a clue.
I once owned a Sako rifle in 300 Win Mag that was Magna-Ported.
Since it was my first experience with a 300 Mag, (and much younger) I could not tell you whether it kicked less or not, but it was definitely loud!
I think that Magna-Porting and braking rifles may have a place on hard kicking rifles, but I personally prefer to either have a better fitting stock, a better recoil pad and a load that may not be maximum in order to reduce felt recoil, or buy a less powerful rifle. I just do not like the extra noise, as I developed a flinch off of that 300 way back then, that I still have to deal with every year. And I tend to flinch from the noise, and not the recoil. (Noticeably less when I wear double ear protection).
My current 300 is a WSM with a custom laminated stock and a good recoil pad, in a rifle that is not overly light. Comfortable to shoot off of the bench with 180 gr AB loads chronyed to 2970 fps. Still full performance without the extra noise and recoil, and won't blast other shooters on the range, or blow grass/dust/dirt/snow all over the place when I shoot it from field positions. Which will disallow watching bullet placement and animal reaction to the hit, far worse than the muzzle jump from the rifle's discharge will in the field.
Another option that you could look at is the 416 Taylor. Similar performance, shorter action and still able to get factory head-stamped brass and ammunition from A-Square.
