The basic search which gives the results in a google page works pretty well. It's just using the Google search engine but limits results returned to those from this site. When you type in your querry and click the search button, if you look at the search box on the google page that opens it will show "223 remington site:savageshooters.com"

On the advanced search, not sure what happened there for you as I just tried the same search and got the usual 4 pages of results.

Couple of things to note on the Advanced search:

1) Your querry has to consist of at least 3 characters for it to work. (i.e. search for "10FP" or "110FP" rather than just "FP")
2) It uses the built in search engine of this forum software which leaves a LOT to be desired.
3) It will only show you 4 pages of results consisting of the most recent result.