From what I have read, Jack O'Connor's 250-3000 Savage rifle was a custom Mauser with a 1 in 14" twist barrel. Supposedly it was used to work up the reloading data in the old Lyman manuals. With a slow twist, it might not have been accurate with bullets weighing 100 grains or more. In one of his books O'Connor wrote about shooting rock chucks with a 25-06.
