Well this thing is getting some new life. Guess I'll give an opinion on cartridge's.
One is all but dead and may pose a problem with ammo, that's the 250-3000. American's are so consumed with speed and power that we've let some of the best go away. With the 250-3000 pretty much gone, the next choice would be the 260 Rem. Again, how long will it last? Not real fast nor even real powerfull, just does the job without a lot of fuss.
I think that this starter issue could be pretty well summed up to use anything you want that's made on the 308 Win case. And I might add, with danger of being whipped by many, has a factory load of at least 120 gr avaliable.