Go to Google's Tools page: [url]http://www.google.com/options/[/url]
and load the [b]FREE[/b] toolbar. While you are on the AR15.com use the toolbar to search within
the site (Search Site).
I just tried it, works fine.

Edit: Oops! Didn't see that GovtThug already posted this! (His has pictures)
[url]http://ar15.com/forums/topic.html?b=1&f=5&t=164185&w=activePop[/url]

Edit 2: The toolbar is easier, no filling in stuff but what you want to search for...