There is a theory about the angle of the shoulder ending within the length of the neck is better for barrel life than a neck that would be shorter. I have not seen any test data. The test would require using cases of the same volume and bullet diameter with the bullets at the same oal and matching throats in the barrels and thousands of rounds fired... and repeated with several barrel makes.
I believe the benefit of the 6mm Remington over the .243 Winchester is longer brass life and higher velocities... They both eat barrels a bit...
I believe the benefit of the 6mm Remington over the .243 Winchester is longer brass life and higher velocities... They both eat barrels a bit...