Note: This procedure requires editing a game file; creating a backup copy of the file before proceeding is recommended. With a text editor, edit the "swat2.ini" file in the "swat2" directory. Add the following entries under the "[Missions Played]" header to access any mission under "Quick Play":
Select a unassigned terrorist/officer at the recruitment screen, then select "Equip". Select the same terrorist/officer from the menu, select his small firearm, then select "Remove Item". Immediately press CURSOR UP or CURSOR DOWN and another small firearm should appear. Also remove this another will appear. This will allow you to get an unlimited number of guns to sell.