I think its about vampires on the trailer theirs an old women crossing the road and then she pulls out a massive gun and I think some the vamps chain them self in a van before the sun comes up so they don't hurt anyone it's a modern film like 2005 and up?

That sounds like Skinwalkers. Skinwalkers (2006) - IMDb (http://www.imdb.com/title/tt0461703/?ref_=fn_al_tt_1)

Skinwalkers is about two clans of werewolves. One clan relishes in being what they are and hunting people, etc. the other wants to be more peaceful and chain themselves up when it is time to 'turn'. The main story is about a boy (and his mother) who is 'special' to the clans and each wants him for their own reasons.

The lady pulling out a gun is shown in the trailer.