Originally Posted by long island leprechaun
Given that we call authorities to report our neighbor making too much noise, or beating his dog, I would guess that this too is reportable. Police may have knowledge of the stockpiling issue (probably not) but may not put that together with your knowledge of erratic/unstable behavior. I'd like to know the neighbor is at least on someone's radar. They could also initiate a MH Crisis team visit, which is pretty common. Again, I would want the neighbor at least assessed and noted by those that might be able to avert a catastrophe.
I agree erratic/unstable behavior should be reported when encountered, if for no other reason then to put the poor soul on someone in a position to help them or in a position to prevent them from causing harm radars.
Of course I am sure you know by now I do not agree with gun registraition.