So if you got shot by a 22LR, would your response "well at least it wasn't a larger caliber or hollow point"?
Or would your response be "fuuuuuuuck I need medical attention"?
You're asking someone to establish a legal definition, which is an inherently arbitrary process. You're literally defining something that is currently undefined. The only thing that matters is that everyone agrees on the definition.
Since short barrel rifles are already defined and regulated (unless you'd like to expound upon the entire sensibility of a 16" cutoff, it's just as arbitrary), I'm simply picking up where SBR leaves off.
I'm open to alternatives that are clear, concise, lack loopholes (intended or not), and are likely to prevent mass shootings. So far you've offered nothing.
Your turn.