Michael Bowen portrays Buck in Vol. 1 & Vol. 2

He is also shares three Half-Brothers (Keith Carradine, Chris Carradine, and Robert Carradine) with the title character's Actor David Carradine, via David's father (John Carradine) and Michael's mother (Sonia Sorel). 

Michael Bowen also appears in other Quentin Tarantino Films (Django Unchained and Jackie Brown, in addition to both films of the present Kill Bill Franchise)