The "NOT a military-style weapon" argument definitely died in 2016 in Caetano. 

Her actual weapon was a stun-gun and the Supreme Court ruled that the  Massachusetts' argument that she should have to be required to kill the father of her children instead of just stunning him to protect herself was ludicrous.

They specifically ruled that even the US Marines use stun guns and so they got to have the same protection as more traditional firearms under the 2nd Amendment.