However, the government should make it impossible for people with a criminal record, and those with mental issues from obtaining fire-arms.
It is impossible to stop private sales.
You cannot and will not ever stop someone from obtaining a firearm if that is what they're after. Yes, the same age old adage that banning guns will work because banning drugs worked is true. The only thing you will ever do by limiting firearms to able-bodied people is prevent them from defending themselves.