Originally Posted by
Blackelk
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.
That's an interesting way of looking at it. I'd say, however, that the more efficient cartridge would be the one attaining like velocities with less case capacity & powder (that would be the SMs). Not sure pressures matter all that much since the same actions (action strengths) are used for the vastly differing pressures produced by different cartridges. Look at the difference between a 7X57 and 7mmRM, both produced in the exact same action.
The 6.5-.284 also seems to discredit that way of thinking as well being a darling of the long-range accuracy bunch while using what would be seen as one of the very first SM type cases, along with the .350RM & 6.5RM. Matter of fact, the 6.5-.284 has almost identical case capacity as the 6.5RM (which should probably now be called the 6.5 R
SM
)