I shot an adult White-tailed doe last year in Upper Michigan with a Weatherby Mark V in 338-06 A-Square. I hand loaded 200 grain Nosler/Winchester Combined Technology Ballistic Silver Tips using IMR-4320 with 30-06 Springfield once fired brass. I shot this deer at approx 125 yards behind the front shoulder. At the shot she rolled over and never moved. Upon field dressing the damage was minimal (double lung and top of heart), compared to my 270 Winchester using 150 grain Hornady Interlock’s and IMR-4831. The 270 Winchester shoots this 150 grain bullets a little faster than the 338-06 A-Square’s 200 grainer but does more damage.
So now the 338 Winchester Magnum beats the 338-06 A-Square in velocity, but if he is shooting like a 225 – 250 grain bullet then the damage would be a lot less then some smaller caliber moving faster. You never told us what bullet, so your facts are lacking. I would choose the 338 Winchester Magnum, over any the 7mm Remington or 7mm Weatherby Magnum, since you didn’t specify.
Justify this round: 338 Winchester Magnum, Yes he got my vote as long as he can place the bullets, no worries.
yooper77