Did that for both magazines and prohibition as well.
What he said in regards to both. I'm adding what i said for more context
Saying that because they're more scarce and hard to come by will reduce the crime is like saying "If we eliminate alcohol alcoholism and all the associated bad things with it will become lower" We tried something like this in the 1920' it was called the prohibition era, the era gave birth to the Mob and Al Capone.
"Alcohol is not firearms. Everyone drinks alcohol whereas owning firearms is not really something everyone does, and if they do do it, it's like an old handgun in their desk drawer. Firearms is a much less practiced activity. Equivalent to maybe just rum by itself and not all of alcohol. And then banning just semi auto magazine firearms would limit that further to like a certain flavor of rum. If all prohibition did was ban a certain flavor of rum, people would have just switched to wine or beer or a different flavor of rum. No alcohol kingpins."
There are millions of handguns that can already accept said magazines and just as many magazines as there are guns. It would require that every law abiding citizen either turns in said high cap mags for destruction or the government committing a completely unrealistic amount of resources to forcefully confiscate said magazines.
"So make the sale of further magazines and semi auto pistols illegal, eventually the older pistols and magazines will wear out and there won't be many produced to replace the old ones."