Biggest one of mine:

Mandatory, standardized securing of the guns. Basic gun safe strength, ability to mount to studs in walls. Mode of entry doesn’t matter…mechanical cypher, biometric, whatever, so long as the lock isn’t easily defeated.

Same with carrying in a vehicle. Bolt it down.

If people can afford thousands of dollars worth of guns they can certainly afford a decent safe.

Edit:

Unsecured handguns account for the majority of firearm suicide deaths in the United States, study finds

Overall, firearms used in unintentional injury deaths were often stored loaded (74%) and unlocked (76%) and were most commonly accessed from nightstands and other sleeping areas (30%).

It is difficult to ascertain the exact number of guns that are stolen from individuals in the United States because many of these thefts are not reported to law enforcement. However, estimates from a number of survey studies indicate that roughly 200,000 to 400,000 guns are stolen from individuals each year…Whether taken from gun stores or from individual gun owners, a firearm is stolen every 2 minutes. These stolen guns are often diverted directly into illegal trafficking networks and end up being used in the commission of violent crimes.

The Largest Source of Stolen Guns? Parked Cars.

All stolen guns are available to criminals by definition. Recent studies of adult and juvenile offenders show that many have either stolen a firearm or kept, sold, or traded a stolen firearm: According to the 1991 Survey of State Prison Inmates, among those inmates who possessed a handgun, 9% had acquired it through theft, and 28% had acquired it through an illegal market such as a drug dealer or fence. Of all inmates, 10% had stolen at least one gun, and 11% had sold or traded stolen guns.

The Southern [of the USA] region has the highest percentage of house-holds with firearms and the least safe storage practices (Okoro et al. 2005). Not surprisingly, most Southern states are “exporters” of guns traced in crime (Mayors Against Illegal Guns 2010).