Stand on Zanzibar
https://interestingliterature.com/2020/11/brunner-stand-on-zanzibar-review-analysis/
The continuing (and ever-expanding) American firearm carnage reminds me of John Brunner's 1968 novel. His "muckers" (amok-running gun nuts randomly shooting strangers) is only one of the symptoms of putting too many lab rats in the same cage. If you've never read this, get a hold of it. Its not just the muckers, its everything else Brunner predicted.