I don't think even the most aggressive U.S.-based gun control groups are advocating for bans on antique bolt-action hunting rifles such as the one used in the Kirk murder, so you'd need more effective regulations than anyone has actually proposed for so far.
I didn't say anything about banning particular weapon types. My brother has several hunting rifles, which he uses for... hunting. He keeps them locked away in a thick steel gun safe in his garage, inside a cupboard to disguise it and dyna-bolted to the concrete floor by
me. He keeps the rifle bolts hidden away in another room. He never talks about guns or hunting in public and doesn't post hunting photos on social media. In short, he's paranoid about people stealing his guns for nefarious purposes. Or perhaps he isn't paranoid, because in New Zealand obtaining a gun license isn't easy and criminals have an even harder time getting them.
It didn't used to be like this in New Zealand, but then in 2019 the
Christchurch mosque shootings happened. The government acted swiftly, banning assault weapons and making sure that gun owners were properly vetted in accordance to the how dangerous all guns are. If the police smell the slightest hint of criminality, instability or slackness you don't get a license. As a referee for my brother I got put through the wringer too, even though I haven't touched a gun in 40 years.
Your description of bolt-action hunting rifles as 'antique' is disingenuous. Gun design hasn't changed much in the last 100 years, and one that was made that long ago is still just as deadly as a new one. Bolt-action rifles are used for hunting because they are more accurate than semi-autos. Most can be fitted with a magazine (limited to 5 shots max in New Zealand), and in the hands of a skilled marksman (ie. anyone who has done a bit of target practice) can be devastating.
The big advantage of a well sighted-in hunting rifle for assassinations is the same as with deer - you often only get one chance for a kill shot. Charlie Kirk was shot from only 430 feet away, but even at that distance it's easy to just wing the target or miss altogether. I doubt the shooter was aiming at his neck. If he had a less accurate weapon he might have missed. Restricting assault rifles is more about limiting the damage when someone decides to kill'em all at close quarters.
Maybe I am advocating for more effective regulations than anyone
in the US has proposed so far (though I doubt that's actually true) but if that's what it takes... And yes, I know it will never happen and the shootings will continue unabated - because that's your culture. Which is why I said that expecting
effective regulations in the US is not practical. Charlie Kirk was certainly right about that.