An AR-15 is a single weapon that can be used in a specific context by one individual to a limited degree. AI owned by major organizations is a highly complex thing that can be used by all sorts of multiple actors simultaneously, at scale, in all sorts of ways ranging from good, to iffy to ambiguous to dangerous to extremely dangerous. AR-15's in the hands of mentally unstable people or those with malevolent intentions of any age can be very dangerous things, but the nature and level of the danger is of a totally different, much more limited type to powerful AI tools in the hands of mentally unstable powerful people, or self.interested leaders and organizations..

Note; Edits for a bit more context.