"make your bones" does mean to commit your first murder in the interest of mob business but it does not make you a Made Member of the Italian La Cosa Nostra. You have to be sponsored by one or sometimes two made members and formally inducted by the high ranking members. Moe Green was never made because he was not Italian. Meyer Lansky and Bugsy Seigal, although very powerful and influential in the national comission were not made guys. I'm sure there were made members who never killed anyone but were highly connected or valuable to the family. Junior Gotti was made by his father but I'm not sure he ever whacked anyone.