I don’t see how the configuration and design of a firearm in terms of detachable magazines, pistol grip, bayonet, adjustable stock, or other irrelevant / superficial features included in prior AWB law counts as free speech.
(But I think I’ve disproved your first point, at least. :))
But I also don’t see how lawsuits against a firearms manufacturer based on people using them to do evil makes sense. Anymore than one would sue Ford for making the car that some sick ass hat used to run into a crowd, say. Or suing Louisville Slugger if a psycho goes on a bashing spree with one of their products.