The 2nd Amendment says nothing about background checks.
Nothing in the Constitution authorizes Congress to require a background check in order to acquire or own anything whatsoever.
I'm quite sure that most people of that era would not sell a gun to a known criminal or crazy person.
Technology has provided the ability to reduce violent crime without infringing on Unalienable Rights in some cases. We're talking about the sale of a firearm in this instance, not merely a transfer...