In a lot of cases building superior long range accuracy is better in a larger case thus being able to use a slower burning powder and a longer barrel. The major bonus is the bigger case and slower burning powder builds it's pressure as it burns down the barrel behind the bullet. The smaller case and faster burning powder has it's pressure build in half the time and a lot of the pressure is right there on the chamber. Compare the two and you'll find the 7mm Rem mag can reach same velocity's with 5,000-7,000 less psi. It's just more efficient if you look at it the other way. A magnum in a 22" barrel is a waste of powder in the first place. Minimum would be 26" barrel for a magnum .338 and smaller. Makes no since to compare apples to apples unless you use something it can gain full potential from.