The Cap was set either at the 1971 or 1976 commission meeting of the five families. They closed the books from 1958 till 1975 for too many members being made and Scalise selling membership into the Gambino crime family. I'll point out that Joe Colombo and Joe Bonanno were making guys on the sneak, Bonanno made 4 or 5 guys, Colombo about a dozen, and after Colombo was shot, the family followed with what Colombo was doing and made about a half of dozen guys on the sneak before the books were reopened.This was so the families would not feel threatened and start making more members, it is a way for the families to have a stable and peaceful co existence. During the 1960s you had the Profaci war, and the Bonanno war. We know that the Bonanno and Colombo families were submitting fake members that died so they could make new members in their families when they capped out to grow. The Gambinos and Genovese seemed to not mind these as it increased those families sizes by 20 members which were not a threat to those two big familes and only after the fact, but the new members they felt belonged to their society. It was when another family found out or knew that it was a fake member during the vetting phase that the problems would start. Meaning the family caught could not make any new members for the rest of the year and pay a huge penalty, money always money with these guys.