I've had the same issue. I've tried an array of 15+ different cap turrets all firing at once at the same vehicle for 15 minutes. several kinds of nukes and even the AMS from black mesa

Update: this is the hunter-killer.
the gunship died so quickly when it touched the AMS that it crashed my game

Well, too bad. It seems a lot of addons get broken since like one year or so by gmod updates. It's sad, because before that you could pretty much use an addon from 2012 perfectly but now even addons from 2018 breaks...