I have never been bluff charged and I hope I never am, but standing your ground is the advice that’s given.
I’ve only had one close encounter with a grizzly. He didn’t charge me, but I thought he was. I was taking a water sample by a stream and I heard this weird clicking sound. Looked all around and couldn’t find the source until I looked up. About 10 feet away above a row of alders I saw a grizzly head looking at me and snapping his jaws. He was standing on his hind legs looking over the bushes. I immediately started screaming at him. He looked at me for what seemed like an hour then he dropped his ears. I thought I was fucked. All I told myself to do was to play dead when he came at me. The pistol and bear spray were in the truck about 20 feet behind me. Well, he looked at me a little longer, dropped to all fours and went on his way. I composed myself inside the truck and when I knew he was gone I grabbed the tape measure and measured the alders at a little over 8 feet. That means the bear was at least 9 feet. That’s a big interior grizzly. If I would have tried to make it to the truck he would have come at me and had me before I would have even gotten close.