He'll No.
Will it kill a grizzly? Of course. But, will it kill it before it kills you should be the question.
That 12 gauge with GOOD slugs is your only hope. Many years ago an article was published in ALASKA MAGAZINE, the author (a registered guide) from Fairbanks and another guide from Kodiak were hunting on Kodiak. A bear came for them and got two 500 gr .458 slugs into him. It still managed to go from 50 feet to 10 feet before it expired. Will any hand gun kill a bear? Wrong question. Will it STOP the bear! Big difference!