Roger, you are old enough ...
to remember that that was EXACTLY how firearm purchases used to be made - walk into the shop, fill out the Form 4473, show proof of age and identity, pay your money and leave with the firearm.
There were less mass shootings then because more homes had firearms and parents instructed their children in their safe use. Many youngsters worked odd jobs and saved up their money to purchase their own rifle or shotgun in their early teens and used their new purchases often and well and safely.
I can't understand how anyone could want to give up ANY of their rights just to "get along" or because others who do not exercise their own right believe no one else should either.
The Bill of Rights was the result of DEMANDS of the delegates to the ratification conventions because a war had just been fought against a tyrant who felt colonists had no rights. The actual revolution started when British troops moved to confiscate firearms of the colonists and the founders wanted it made clear that it couldn't happen again because the government was granted absolutely NO AUTHORITY of the right of the people to arm themselves and use those arms. Laws passed to punish the MIS-USE or arms are wholly appropriate as they do not infringe upon the basic right.
Tench Coxe, of Pennsylvania said it rather well and clarified WHO the militia is and exactly what arms the citizens of this country have a right to keep and bear - "Who are the militia? Are they not ourselves? Congress have no power to disarm the militia. Their swords and every other terrible implement of the soldier, are the birthright of an American . . . . The unlimited power of the sword is not in the hands of either the federal or state governments, but, where I trust in God it will ever remain, in the hands of the people." -- The Pennsylvania Gazette, Feb. 20, 1788
Note that "Their swords and every other terrible implement of the soldier, are the birthright of an American ." indicate that the founders were aware of new technology in weapons and expected the citizens to be able to arm themselves equally as well as any domestic or foreign soldier whether friend or enemy. These weapons are the very type the gun banners now want to take away despite their being exactly what the founders had in mind that government has no power to infringe upon.
Again today several million legal and responsible owners of these so called "assault weapons" killed or injured no one illegally although several thousand of these same owners did prevent criminals from doing such things.