"I happen to know one writer very well who will not test any rifle unless he has a wide variety of factory ammo or can handload for the rifle. He also doesn't go on very many "industry hunts," and if he does, he doesn't write an article just about that limited experience, but also tests the rifle (or scope, or bullet) thoroughly in other ways. And there are enough magazines that are interested in his articles that he can make a fair living at it. And I know several others who pretty much operate in the same way."
