Mickey Rourke called on his longtime friend and Hells Angel Chuck Zito to help cast The Last Outlaw. Chuck called some of his biker brothers from Oakland, California to star along side of Mickey to be part of his posse. Mickey wanted rough cowboy looking types, Zito hired Elliott (Cisco) Valderrama, Edward (Deacon) Proudfoot, Marvin (Mouldy Marvin) Gilbert and Darryl ( Little Darryl) Shay as the posse.
The former soldier who becomes an outlaw and has never recovered from the Civil War is extremely common in Westerns - most obviously Clint Eastwood in "The Outlaw Josey Wales", 1976.
Paul Ben-Victor who has a small part in the movie also appeared in another more successful Western released in the same year - "Tombstone" with Kurt Russell and Val Kilmer also released in 1993.
Dermot Mulroney played a similar role in "Young Guns", 1988.