 If you liked
Gun Blaze West
|
 ...then you might like
Peace Maker
|
Both has a revolver men or boy in a quest for something;
It also include assassins/ evil guys with no particular development;
Both mangas have duels;
The main character is in a quest for a mysterious missing parent (in Peace Maker for a person related to him, in Gun Blaze West for a [dead] friend).