alot of your barrel life is determined by what ya shoot through it, I know 1 guy who has a 270/338 Rum imp. that has 900 rounds down the pipe with no or almost none erosion in the throat, he shoots ultra slow ball powders, they're sensative to warm weather but easy on barrels. I was told by a smith that WC872 was easier on barrels than H-1000 so I shot a 3 shot group with H-1000 through my STW, the barrel was 2 hot to touch, shot 5 with 872 and the barrel was just warm, it has to effect the erosion some, less heat has to account for less erosion.
My 7mm/338 lapua imp. has 122 gr of H2o case capacity and shooting 872 I fully expect to get 1k+ rounds before I rebarrel.
JS
BTW case capacity on the gibbs is 73.7 gr of H2o