Yes.
1. Go to the Marketplace section, and click on any sub-forum, say HK PISTOL FOR SALE.
2. In the selected sub-forum, click on
Search Forum link, then select
Advance Search.
3. On the
Advanced Search screen, enter your keyword in
Keyword(s) field (e.g.: P7M3)
4.Right below it, in the
Search in Forum(s) drop-down list, select all the sub-forums that you want to search. Hold the CTRL (or Command if using Mac) key while selecting the sub-forum if you want more than one sub-forums.
5. Then click the
Search Now button