From what I believe, that law is really not needed in the state of GA..
In the state of GA... if you knowingly sell a firearm to someone that is not eligible to buy it...
And they commit a crime with it... YOU can be held accountable.
(NO, that is not a typo).
The easy way around this: GA law says having a copy of a current (not expired) GWL (GA weapons license, the state version of a CCW permit)...
Is valid as a background check.
Most of the gun owners I know follow this personal policy when selling a firearm:
The ONLY person they would sell to: has a GA drivers license with a GA address and a current GWL.