How long does it take to decide a question is "unanswered", an hour? week? year?
I say leave them up, eventually someone may find the answer and post it; or the guy that knows will finally see the posted question.
JMHO.
I'm not sure your "7 round" post should be deleted either- obviously at least one mag holds only 7 rounds; why is the question, again JMHO.
I say when it doubt, leave it up.
My pet peeve is disappearing selling prices!