All I can remember is the man that travel's in time, travel's back to the medieval times. He is missing a hand and uses a chainsaw with it. He also carries a 12 gauge shotgun along with him as well. I believe his quest is to find a Necromancer Book in order to travel home. Does anyone know this movie title?

Sounds like the end of Evil Dead II and the start of Army of Darkness.

Here's some links for them both:
Evil Dead II (1987) - IMDb (http://www.imdb.com/title/tt0092991/)
Army of Darkness (1992) - IMDb (http://www.imdb.com/title/tt0106308/)

Army of darkness