My guess is that some scalpers have purchased bots that are programed to find and purchase set items automatically. Since they put up new inventory at different times with no set schedule I can't see a regular individual getting lucky enough to catch multiple items for a large order.
That's similar to what I was told by somebody who is more tech savvy than me.......
And I applaud Powder Valley for doing this.
Although Midway is doing the same thing with powder, primers and bullets.