As snookie so aptly pointed out, that is not what I said.
I said, taking away a gun or gun type from legal owners means those guns will not fall into the hands of thieves when they rob you.
If there are no AK's in the home or gun shop, then there are no AK's to steal from said home or gun shop. It's not a difficult concept to understand.
Except no one, almost no one, is proposing to outlaw guns already in existence. And if they did, criminals and many others would continue to own and acquire them.
There are plenty of full auto guns out there illegally, despite their being effectively banned 80 years ago.
So stopping production now of AR's etc would do nothing about the 30M or so already in circulation. Stopping sales of hi cap mags will do nothing because there are about a gazillion hi cap mags in circulation. Actually it will do something: it will drive up prices, making them attractive targets for theft.