I don't know about house to house. How did they do it in Australia? However they used the police to do it there, my theory—or hypothesis, I guess—is that if they did the same here, communities of color would certainly be cleaned out of their firearms, and white communities would go largely untouched. Is that a good thing?
Sure, you'd possibly get some reduction in certain crimes, but is uneven application of the law, in which historically-marginalized communities are the most heavily-policed yet again, the only or best way to get there? Seems to me this would be such a very clear and obvious case of othering that it would create an uproar.