There was a group of pot heads on every base in Vietnam. I wasn't one of them. I guess everybody dealt with stress in their own way. I worked on heavy equipment & couldn't do that safely if I was impaired. Heavy equipment is dangerous at best & being impaired is like playing Russian roulette around any machine including trucks. Heroin was easy to get also & it wasn't cut like most of it is here today. I know a person very knowledgeable on drugs. Drugs seized in a drug bust are analyzed. The more pure the drugs are, the higher on the echelon the drug dealer is. Often common flour is used to cut the drug. Drugs may be cut several several times before it gets to the user.