Ive shot alot in my life , but i've mostly used mild mannered hunting cartridges (30-06, 223, 308, 22, ect) and ive usually sold the guns and bought others before barrel burn out occurred. So my question is in a relatively hot cartridge, say a 7 mag, or 280 ack, or 6.5 x 284, 243 ect- is the barrel life better using a heavier longer for caliber bullet at a lower velocity or a faster shorter bullet?

Example- 6.5x284 123@3250 vs 140@2900 ? 1-8 twist
- 243 55 gr @ 4000fps vs 105 @ 2900? 1-8
- 7 mag 130Gr @ 3300 vs 180 @ 2900? 1-9

Or is there a happy medium? my initial thoughs are a faster bullet will wear out a barrel faster, but a heavy bullet also has to have a faster twist and has more contact with the barrel since it was longer so im not sure. So what do you guys think who have burned out multiple barrels? is there a difference or a happy medium?