Elk are no problem for the great 375 Win.The keys are these:good shot placement,good high quality ammo intended for use on large game,and reasonable shooting distances.A few years back a friend of mine took a large 6x5 elk at 165yds in Arizona,with one shot.He was using a Savage M99A in 375Win,with 235gr Speers at around 2400fps.
The key when using ammo intended for much hotter rounds than the 375Win.Is to get velocity high enough to get good penetration,and so it will also give you the mushroom effect seen it the hotter rounds,like 375 H&H.