As a small amount of metal can be added at the end to make the weapon 'legal', that act does little to address the numerous¹ problems beyond being able to sneak a gun past airport security. Hardly an important milestone in controlling anything. It didn't even affect any gun in existence at its time.
But more generally, as we all know, a ban without provisions for enforcement is useless. Compare to the CWC (Chemical Weapons Convention) which I point to as one of the best pieces of international "coming together" via treaty. It includes requirements that member countries submit to inspections from its enforcement body (OPCW) and furthermore that countries can request the OPCW inspects another member country if they suspect non-compliance. It also includes restrictions on transfer of various chemicals in order to incentivize non-member countries to become members so they can purchase chemicals for industrial purposes from other members.
¹ and bigger, if you're modeling this from assumptions where it's a problem at all -- not everyone thinks it is, "an armed society is a polite society" etc.
But more generally, as we all know, a ban without provisions for enforcement is useless. Compare to the CWC (Chemical Weapons Convention) which I point to as one of the best pieces of international "coming together" via treaty. It includes requirements that member countries submit to inspections from its enforcement body (OPCW) and furthermore that countries can request the OPCW inspects another member country if they suspect non-compliance. It also includes restrictions on transfer of various chemicals in order to incentivize non-member countries to become members so they can purchase chemicals for industrial purposes from other members.
¹ and bigger, if you're modeling this from assumptions where it's a problem at all -- not everyone thinks it is, "an armed society is a polite society" etc.