That is a problem that alot of private clubs face. There are no babysitters and some ignorant people really need them. I'm not being mean but there is alot of people who were never taught about proper targets/ target placement/ ricocets/ gun handling/ ect. And then there's the totally inconsiderate ones who just don't care, ( destruction of property).
Limiting the membership won't effect anything but the books, we have say 200 members and only about 50 are active users. About 20 show up to vote on how 200 membership dues are to be spent. That's pretty good on one hand, but then on the other there is alot of members you don't have a clue who they are/ or if they are members.
Rules and regulations, signage, more volunteers to police the range and threatening of enforcement might help the situation, but I would doubt it will work. You'll have to catch them doing it, Know who they are, and report them to the board. I would absolutely do this myself, but couldn't expect the general membership to.