Pretty much myths....
Yes, minorities were enslaved, abused and killed but it wasn't because of drugs....as a matter of fact racism was used as a reason to ban drugs at the beginning of the 20th century. Weed was being used by blacks to seduce white women....opium was associated with Chinese immigrants...etc..
There is one recorded high noon style shootout in the old west...much like today you shoot your enemy in the back was the norm and that was rare because social norms are self supporting. You are less prone to commit crimes and be more polite in general when everyone is armed; It's the same reason you don't go into a job interview and tell everyone to go fuck themselves...