My dad is a major offender of improperly using "clip". He's 53 and he has known clip as the "proper" term for magazine most of life. I constantly correct him on this, but you can't teach an old dog new tricks.
I was teaching my friends how to professionally use guns today and one of them commented on how the gun wasn't loaded with an "ammunition clip". I took the gun away from him and chastized him until he got the message. I don't tolerate improper designation!