'Register your guns and you won't have to worry about it. Oh wait, you're talking about a 'friend.' Or a 'friend's sister.' Anyone but yourself, right KFC? You'd never own an illegal gun, right?"
Depends on where you live. Guns don't have to be registered in most places. If you move to a new area and go to the police department and tell them you want to register the ownership of your guns they'll look at you like you're a nut. You mostly see that in crime-ridden urban cesspools where it doesn't help anyway.
In fact, it makes it worse. Such places draw illegal gun dealers, much in the same way that bootlegging and drug crime always seem to be worse in "dry" areas. If you have a legal gun store with fewer hitches for purchase, it's actually HARDER to get a weapon to use for crime.
Why? Because in places where it is almost impossible to get a legal weapon, illegal ones are a hot commodity, and people sell them on street corners. Dealers in illegal weapons have a hard time making a living in areas where it isn't so hard to buy guns legally.
Forcing people to jump through hoops to buy guns, and making it inconvenient to own them just makes the dealers who don't do those things popular. Then you have a community full of "cold", cheap weapons.