Its really not all that crazy. .22s are cheap, might as well have a ton a guess. But 5k and less of all his other main systems is really not that over the top. Considering you can burn through 1k rounds a running a gun hard, it makes 3000 rounds not look like such a huge number.
I would keep on hand that type of ammo, but it seems like every time i get a head in my tiny stock pile it gives me a reason to take a gun class, reasoning is "hell its sunk costs, might as well burn it up".. Which results in much less ammo haha, but thats why we buy it.. to shoot it!