Its a MiniGun weapon for OFP!
ADDED UNITS:
under West / men:
"SMC GAU Soldier (MG20mm)"
ADDED WEAPONS:
SMC_GAU (MG20mm)
NOTE: In the editor in ammo boxes use :
Nameammobox AddWeaponCargo ["MG20mm",..]; Nameammobox AddMagazineCargo ["MG20mm",..]
Read it, there must be a new west soldier in your Mission Editor, open it press F1 and look into west - soldier.
The only problem that may be hapening is if your copying the addon to a wrong place or if it's in a folder and you placed it with a folder.
All you need to do, is to copy the file or files .pbo into your operation flashpoint addons folder