In factory ammo not alot of difference in velocity. But beings this is the reloading column I'll throw in my 2 cents as well. The difference between the two to a reloader as far a velocity and tragectory is concern is about four to six grains of powder. You can load more powder in the 300win mag case without the pressure problems of trying to cram powder in the 300wsm case. Most reloaders know how much 4 to 6 grains of powder will increase a load for velocity. Lets just say its quite a bit. That means for a reloader the edge of tragectory goes to the 300winmag. But as long you just shoot factory ammo all the time they are pretty much on equal ground.