Did you check cartridge protrusion from barrel before installing ? Do you have both go and no go gauges ?f
Take a magic marker and blacken the extractor groove and above , place in bolt and hold against face , spin slowly, see where the extractor is riding . It's just an aprx location but mark it again and this time chamber , close bolt , pull trigger ( NO PRIMER ! NO POWDER ! NO BULLET ) open and see first if ball is still where it's supposed to be and second where the extractor is hitting when chambered and pulled out .
Better hit the bear with the first shot.
Just a word of caution on swapping bolt heads -- be sure to check headspace. Bolt heads are not held to tight tolerances on economy rifles.
Better get you a glock 20 or a s&w 460es to carry after them ole bears.