In America there will be considerable opposition and non compliance with such a law, so it may not be as effective as it has been in countries like Britain, Australia and China.
Generally any attempts at gun regulations in the US have been pretty weak, full of loop holes and ineffectual. There is little point in regulations which only apply in one state for instance. No point in rules for gun shops which don't apply to gun fairs. Unlike heroin and cocaine, its fairly hard to smuggle guns across a secure border (they are pretty bulky and usually made of metal, although plastic guns made on 3d printers may become common in future), but there are a lot of guns already in the USA.
IMO, gun control is rather like drug control. Social attitudes are at least as important as the law. Whatever the law says, many recreational drugs are accepted in certain circles in the USA, and people freely break the law. In some Muslim countries, alcohol is not entirely illegal, but social pressure stops people from falling down drunk in public. China has drug addicts (about a million), but you wouldn't know it if you visited there, except possibly in some ethnic minority regions. China has draconian drug laws which are totally failing to make drug addicts quit. Solitary confinement for a year for opiate possession, forced withdrawal and a 99% relapse rate. However the general public are largely unaware of this. It's out of sight and out of mind. However any illegal drug use, like gun possession is totally socially unacceptable. The country had opium wars in the past.
The USA has legal alcohol for over 21's (absurdly high age IMO) but generally alcohol is accepted. Frat boys rarely say "no beer, thanks, I'm only 20". Prohibition failed because a significant percentage of the population still wanted to drink socially, in social environments where it was accepted.
A significant proportion of the American population love guns and regard the love of guns as patriotic, a large number also want guns because other people have them and they feel threatened. Criminals find it easy to get guns because legal and illegal guns are so common. Burgle a house, you might well find a gun lying around (not in a locked cabinet).
In this climate,gun laws will always be watered down, people will break them, gun advocates will claim they don't work while trading the huge stockpiles of weapons already in the USA.
Gun control COULD work in the USA, IF the public is fully behind it.
I don't want the total abolition of guns, I support hunting and pest control, but the notion of people being permitted to carry handguns in the street, concealed or unconcealed is absurd to me.
The rest of the world watches US gun culture with disbelief, sees the regular mass shootings and the Americans saying that "guns don't kill people, people kill people" or declaring that we need more people with guns to shoot the mass shooters.
Suicide is more common when people can do it quickly and easily. When domestic gas supplies were poisonous there were more suicides from people sticking their heads in ovens. Likewise, very few mass killings are performed by lone nutters with knives or hammers. It takes too long, and you have to get very close to your victims