The Lewis and Clark soldiers fired 10 shots into a 500-600 pound grizzly and remarked that the Grizzly was extremely hard to kill. In their journals, they said: "we Shot ten Balls into him before we killed him, & 5 of those Balls through his lights.”
After the bear was shot 10 times, Lewis wrote: “he swam more than half the distance across the river to a sandbar & it was at least twenty minutes before he died; he did not attempt to attack, but fled and made the most tremendous roaring from the moment he was shot.”
I read a fairly scientific study that queried Alaskan bear guides about the rifle calibers used and the effects of the hits. The data gathered indicated that the 300 magnums resulted in a larger percentage of clean kills than the .338 magnum.
I'm sure a 30-06 is a fine Grizzly cartridge, but I would use those Hornady Light Magnum loads if I were using that gun on a Grizzly hunt.