Not a chance. I burnt out a half dozen or better 300RUM barrels shooting 110's and I was pushing it hard to get 4200 with those, even with a 30" 15 twist. 4200 with 124gr coppers isn't going to happen unless you go way over max pressure and even then I doubt it.
4000 from a good 26-28" barrel is probably doable with safe pressure. Just don't expect more than 600-800 rounds out of a barrel even if you're trying to keep it cool.
300RUM with light bullets is probably your best bet as long as there's no wind. The light bullets at 300-400 yards will still be blown around by wind enough to mean a miss or wounding an animal so you can't just pretend wind doesn't exist because you want to be too lazy to dial the easiest equation.
Personally I'd get a better choice for a deer rifle, a LRF or BLRF with built in ballistics and an optic with a simple tree reticle like the Swarovski BRH and teach the dude how to shoot. He'll be more successful that way than thinking he can't just hold the crosshairs straight up inside 400 yards and get a clean kill.