The Barret M-00 is a so-called anti-material rifle. It uses complex, high-energy technology that Barret has done a great effort to keep sealed and safe inside the gun. This also means you cannot repair it yourself should it happen to malfunction. The 'William' is the only known successful attempt at modifying the gun. Deirdre Lux was of course the one to make it. It's called William after her second son.