I've never played Paintball, but Bari Ve-Shema has a post on whether or not it is permissible to play it (link).
I'll note that the same issues are raised regarding boxing, and discussed by R. Daniel Z. Feldman in his classic The Right and the Good: Halakhah and Human Relations (link to relevant excerpt).
Wednesday, May 24, 2006
Paintball
9:25 AM
Gil Student