Perhaps a description.ext file. Put it in the appropriate mission folder when you have exported your mission to one of the mission folders (OperationFlashpoint\Missions or OperationFlashpoint\MPMissions).
Here's what a description.ext file might look like:
class weapons
{
   class svddragunov
   {count = 1;};
   class ak74
   {count = 10;};
   class rpglauncher
   {count = 1;};
   class at4launcher
   {count = 1;};
};
class magazines
{
   class svddragunov
   {count = 10;};
   class ak74
   {count = 24;};
   class rpglauncher
   {count = 3;};
   class at4launcher
   {count = 1;};
   class mine
   {count = 6;};
   class pipebomb
   {count = 3;};
   class handgrenade
   {count = 36;};
};
You can add or change the weapons to this as long as you have the right weapon names. There's a good list in the RS OFP Editing Manual of weapon names. I think the manual is in the Getting Started section of the tutorials in the Ed Depot.