Barrel life shouldn't even be a consideration with a big game hunting rifle. The 7STW is a might large IMO for a varmint rig, and I don't think I'd want to have my competition rifle chambered in that round, either ,, even though it can be extreamly accurate. Consider this,,,, there's one source of brass currently. Sometimes its available sometimes it "out of stock". It'd be the s@(%^ to have the rifle built and wait for two months on ammo/brass. In this day and age, plan ahead.......
Besides all of that, isn't your Douglas barrel a .30 caliber? Your going to have a hell of a time chambering a 7mm cartridge in a .30 caliber barrel! Reading comprehension in this thread is terrible! Must all be products of our public education system!