When our founding fathers created the constitution they were pretty focused on issues which had been abuses or led to abuses of the people by oppressive governments in Europe. They were not trying to tell people how to do things like raise their children but the did make rules that would prevent an oppressive government from disarming the people so they be oppressed without risking an armed rebellion.
The constitution is a short document and doesn't deal with common sense rules, like don't leave your loaded guns or sharp knives where young children can get to them. Similarly I can't imagine they would have thought they needed to explicitly say we need to keep guns out of the hands of known violent criminals and mentally unstable people because they probably though that was common sense and the Constitution is not an Army Regulations Manual.
Our job should be to attempt to use common sense to protect the public while at the same time not enacting laws that nullify the 2nd amendment by unfairly restricting the constitutional rights of most of the people.
That's a little tough with the second amendment, but hardly impossible. Lets take registration:
If the government has accurate lists of all the guns, they can easily circumvent all our other rights by seizing all of them first. That has happened in other countries. Fortunately all inclusive lists are not necessary, it's only necessary to keep lists of the people, who are not allowed to possess them. Oh but anti gun folks want everyone who owns a gun on the list... WHY?
The only reason to put every gun owner on the list is so that we can demand their guns if one day we want to.
Instead of respecting the Constitution we regularly make laws that could be used for confiscation, and it's those laws that most gun owners get upset about... and the ones that just make it tough for them, (but not criminals), to buy, own, transport, and use their guns.
Waiting periods have no effect on criminals, but somehow we imagine the people who buy guns and the public are better off if buyers have to wait a few weeks and make two trips before getting another gun. I say another because most gun buyers already own several. Today we have computers that can tell any vendor if any one of your credit cards has reached it's max limit in a few seconds. A cop can tell if your drivers license has been suspended in a few seconds. Making a gun buyer wait weeks when it should take seconds is not necessary, it's a burden anti-gun folks enjoy inflicting on law abiding gun owners, that they know has no effect on violent criminals.
If someone is not on the "no gun" list, they should be sold the gun with no other questions asked and nothing but a sales receipt as a record of the sale. That way criminals and the insane couldn't buy them and the government wouldn't have a list that could be used to disarm the general public.