Interesting question, do not remember reading that myself. The first was in the Yukon, both Fred and Guide, Alex thought it was a black bear, it had been raining. Fred shot the Mountain Grizzly with his new Bear Razorhead, without his side-arm, which was on his horse, or the guide as backup.
He shot at least one in BC for the Outdoor Sportsman show with Curt Gowdy, and one with Fess Parker in tow. And, he spent some time in a tree, waiting for one to leave, after charging.
He took at least one Coastal Brown Bear (Grizzly), from behind a rock on the beach.
He shot two Sea Bears (Polar), one was stopped with by a backup when it charged, but they are not Grizzlies. He killed two Polars, one of the mounts was stolen from the museum.