It's easy really... smuggle a little bit in every day and build it!
When I was in the US Army I got stuck working in PLL (Parts and stuff) to try and help them out.
Bottom line. After about a month there I figured out they still had EVERY part for M-14A1's available for order.
I passed....rumor control says many other's didn't.
"I have but one lamp by which my feet are guided, and that is the lamp of experience. I know no way of judging of the future but by the past." Patrick Henry 1775
I personally believe in the tooth fairy, Santa Claus and that deficit spending is sustainable forever. We really do need more Admirals in the Navy than ships and that millions of more poor immigrants will jump start the economy.
"There's a sucker born every minute." Phineas Taylor Barnum