According to the story the bear took a rifle round to the chest and still took several shots with the 10mm to bring it down. Without a rifle round to the chest the outcome may have been different. That was one massive bear.
Sounds more like he was just dead set on shooting a bear with his 10 millermeter and the Bow was just thrown into the story.
In the end it took four 10 mm bullets and an unknown caliber bullet from a rifle to put this bear down after traveling 2 miles or so after being wounded by the 10 mm.
Do the math and never hunt in Grizzly country without a large caliber rifle 300 mag or greater.
My choice would be 338
Nice bear though.