You might have to submit to a drug test if you ...
Start a new job
Apply for welfare
Play professional sports
Need financial aid to pay for college
But if you want to buy a gun, no drug test, if you're in a state with no background checks. Also...
Convicted of violent crime? no problem.
Convicted of rape? no problem.
Convicted of selling heroin to minors? no problem
Have an order of protection against you? no problem
Gun laws won't keep guns out of the hands of law-abiding people. Kind of like car laws don't keep people from driving.
But car laws do help limit speeding, drunk driving, and other dangers associated with car ownership. Nationwide gun laws will not keep hunters and other recreational gun users from their pursuits. But they will help to reduce dangers associated with guns.