I think increasing the age makes more sense.

Registry and bans are stupid and just more ways for the oligarchy to control the people. They do want the populace disarmed, easier to enslave that way.

Frontal lobe doesn’t finish developing until age 25, it affects decision-making, empathy. Younger ages are thus less able to control behavior. There are also hormonal differences in brain development which could be considered. Socialisation is also a factor.

Perhaps also change the age at which people are legally considered/charged as adults, since the brain is not fully developed at all at age 18 (or even younger, some children are charged as adults in court). Younger people’s brains are more malleable than adults - there is a greater possibility of reduced recidivism and change in behavior for them that should be recognized in sentencing.

Raising the drinking and smoking age to 21 has had a positive impact, I don’t see why it wouldn’t work great for gun violence as well.

But I think there should also be less glorification of violence in culture (especially that accessible to kids) - that has a big impact on whether they see it as acceptable to commit violence, such as gun violence.