To stay on topic, Glen I think a great deal of context is required. It’s a good question, with a lot of different outcomes. Are the heirs gun-savvy? Two of my children understands the issues quite well. Two don’t (one is 3 to be fair). My 24 and 14 year old are quite educated on guns, and the associated political issues. My 12 year old? She will never have interest. Anything left to her would be sold for what she could get. If she knew it was not legal, she may would give it to an older brother or sister, if they took it. Either way she wouldn’t hold on to it nor subversively black market sell it.
Another question... are we talking about something made illegal last week, last year, or last century? I would not accept an unregistered machine gun as an inheritance. I wouldn’t hold onto it “just in case” they became legal or the remote chance that they are semi-useful (honestly not really) in some form of revolution (which has like a .01% chance of happening). That is long standing law not likely to be overturned, and lets be real revolution is little more than talk of “playing gun.” However, were I to receive 30 round magazines in the will when they were made illegal only a year ago, I might would tuck those far far away in the event that case law strikes down their restriction. To some gun guys, something so mundane as the “stroke of a pen” illegality last year might be an acceptable risk. Same thing with my kids. I’ve raised them to be good and not steal, kill, do drugs, flagrantly break the law, or otherwise harm others. I’ve taught them to obey the law, same as I was. I will say a law that makes an object or activity illegal, which was otherwise perfectly legal your first 20+ years of life and doesn’t hurt anyone, might not be perceived as “legitimate.” Lots going on there.
And to the argument that prohibited items are relegated to the hole you buried them in... there are still millions of people who shoot on private land. No one will know if you have a bayonet lug or not from a mile away. They won’t know how large the magazine capacity is. Obvious things like full auto fire is easy to hear. Disciplined use of an AR15 “assault rifle” is less obvious.
On to the general “revolution” talk... and slightly off topic. I’m of the opinion that no such drastic resistance will occur unless gun control in enacted radically, swiftly, without grandfather clause, and with confiscation. The only way ther will be significant forcible resistance to a gun control measure is if it’s not incremental, bans overnight a commonly owned firearm (yes an AR fits here), has no grandfather clause, and is combined with door to door confiscation. Take any of these legs away, and massive forcible resistance goes away. We all know the anti-gun lobby loves incrementalism so none of this will happen. It’s also why I am ardently against any incremental measures that make a current legal item illegal, or restricts persons to own them without due processs.