Converting a .223/5.56 AR to a .22 is easy either through a dedicated upper or swooping out the bolt and the magazine, both of which are available from a number of sources. Lower's I've seen don't have a caliper indication. So considering rimfire is not covered under the ban, can we simply convert our rifles to .22? This is hypothetical of course, don't see why someone would do this if they can just as easily register their rifle. But what do you think guys, legal?