It occurs to me that the credit/debit card companies could be helpful in these cases, by flagging up large purchases of suspicious items to the security services. As could the suppliers of arms and ammo, if legit and wanting to stay legit.

There must be a threshold that even NRA members would recognise between normal supplies for normal purposes and stocking up a small army quantities.

At the very least, a sudden rush of purchases should surely alert the normal programs which spot if a card has been used to purchase, for example, £2000 worth of French wine. (That's what my stolen details were used for.)

Not just armoury stuff, either. Fuel oil, fertiliser, hydrogen peroxide and so on, as well.

Penny