I hear 1200 rounds for a 6.5X284, but I think thats optimistic. At a match Saturday I was in the pits chatting with Bret Solomon, who is one of the top F-class in the world. He says about 400 rounds is max for his barrels, anything over that is for practice etc. he buys Kriegers by the dozen. He told me the throut erosion for just one match, and I could hardly believe it. Last year every match I shot with him at, he cleaned the target of course, but his X count was unbeiliveable. A sixty shot match he woud have a 600 with 57 Xs. These were 600 yard matches, this year they made the target much harder, Saturday he droped a couple points. I shot my AR15 in Service rife class at the same match, what a contrast.
You might consider the F/TR class, which is Fclass, but limited to 308 or 223, and you use a bipod instead of a rest. I don't know of any round with better barral life better than a 308. Since you have a 308 that would be the way to start.
The Swede round is a barrel burner also, other choices that are popular are the 6XC or .260 Rem (6.5-08) which is what I use at 1000 yards. I sling up and mostly use iron sights.
The 1000 yard matches I shoot are at Camp Grayling in Michigan, there are more 308s on the line than any other caliber, and most use iron sights. Palma is real big. This coming weekend is a three day Palma/long range match, and F-class is always welcome.