I don't have all the information about this picture, but the hunter was Will Gay and the bear was taken in 1997 on Uminak. The bear is the 8th largest on record. The rifle, the person knowing most about the hunt, thinks, is a Army Navy sidelock underlever 450.

More details:
http://www.24hourcampfire.com/ubbthreads/showflat.php?Cat=0&Number=846760&page=0&fpart=1&vc=1&nt=5