A friend has the rem elk foundation 300 ultra mag>I shot it and it is very accurate,he has a muzzle brake on it and I couldn't believe the light recoil on that light rifle.it was like shooting my 260.Think he said that he uses 102 grs of powder so you won't get to many rounds from a lb.He doesn't shoot it much because with all that powder it heats up FAST.I shot it at a rock @400 yds and watched the rock explode through the scope it was awesome,
Another friend has a win mag and have seen him shoot one hole 3 shot groups with it,
A young fellow has a 300 wby at the range and have never seen him shoot good groups with it.
The fellow with the 300 ultra and I and another friend was shooting clay birds at 500 yds,he shot the ultra,me and the other were shooting 270 and 300 wsm and hit just as many birds as he did.
I too would go with the 300wsm it does quit well.This is my limited experience with all four.