Responsible gun owners have a duty to keep guns out of the hands of criminals. If you are forced to surrender your guns against your will make sure they are useless. Just in case they get lost on their way to be destroyed. For safety.
A dab of JB weld in the chamber should do the trick. Once the bolt closes, it ain't ever shooting again.
EDIT: To all the folks saying "Muh 1776!"... Only a small percentage of Americans went to war with the redcoats. A lot of people comply, for many reasons. This is for them, retailers especially, they can at least guarantee these guns don't go to Ukraine, Syria, ISIS, Gangbangers, etc.
Mass shootings would be rare here, too, if 1) cops were allowed to do their jobs correctly in the solidly blue leftists cities and states, and 2) we didn't have a corrupt Intel community purposely mind fucking people into becoming mass shooters, and 3) we didn't have a corrupt Intel community actively training such people with skills you would really only learn in a combat setting, and 4) we didn't have a corrupt DOJ, HSC, and Intel community working in tandem to flood our cities and gangs with true assault weapons.
And, really, mass shootings are rare here in the U.S., when compared to other crimes.
The problem, like with the rest of society all over the globe, isn't The People, it's the governments working to keep us divided on every issue imaginable that is plaguing our society, including the gun debate.
Pretty sure all modern mass shooters were on SSRI’s, too.
Well over 90% of mass shootings are in so-called "gun free zones," where the shooter understands there would be essentially zero chance of being opposed by anyone with a gun. He has a free ride and he can take his time. Reloading is no problem, so magazine capacity limits have no utility. I have taken to calling these zones "shooting galleries," because of this fact.