The only link I had is inactive as well - the Army's RIA used to have a wonderful website with tons of small arms info from their ACALA office. Alas, some Clintonite goon made them take it down and now all you get is pages and pages of mission statements and other such useless dreck. It was a real loss to those of us on the MilHist-L research list.
Sometimes, however, you can still find those pages online. Several mirrors were made and some are still on the server at RIA, just not publically indexed. Try a web search, using Google or AllTheWeb, using such terms as "GAU" or "chain gun" and see what pops up.
Ken Strayhorn
Hillsborough NC