A Sort-of western

[Ed, Ego and Superego]

This one is a big mystery.  It is not a B-film, though it might not be a "good" movie either. 
This is a sort of westen from probably the 50's or 60's, but don't hold me to that.  Setting is the west, but not really the old west...possibly the 1910's or 1920's.
  A couple of guys want a treasure (maybe a weapons dump?) down in Mexico.  They get in trouble, but a guy in an upstairs balcony saves them by throwing a couple of hand grenades around.... they are sort of his weapon of choice.  He's an arms dealer looking for a quick score and comes along with them.  They get there after long adventures, and I think the treasure is actually worthless, or similar. 
This is REALLY vague, I know.  What sicks in the mind is the hand grenade totin' guy.
-Ed

[JJ80]

Possibly either "The Mercenary" or "Companeros", two "Zapata Westerns" directed by Sergio Corbucci and starring Franco Nero. It sounds vaguely like "A Fistful Of Dynamite" but the John Mallory character (James Coburn) seemed to only ever use sticks of dynamite or a flask of nitroglycerine rather than grenades.