Showing 33 of 33 firearms starting with "O"
| Name | Manufacturer | Caliber | Type |
|---|---|---|---|
| O/U Combination Gun | - | - | - |
| O/U Shotgun | - | - | - |
| O/U shotgun | - | - | - |
| OA-93 | - | - | - |
| OF 37 hand grenade | - | - | - |
| OICW | - | - | - |
| OP-SKS | - | - | - |
| OP-SKS Rifle | - | - | - |
| OSP-30 | - | - | - |
| OSP-30 Flare Pistol | - | - | - |
| OSS Pistol Glove | - | - | - |
| OSSh-42 Flare Pistol | - | - | - |
| Oberndorf Mauser Sporter | - | - | - |
| Oerlikon 20 mm Cannon | - | - | - |
| Oerlikon 20mm Cannon | - | - | - |
| Olympic Arms K23B | - | - | - |
| Olympic Arms K23B Tactical | - | - | - |
| Olympic Arms K3B Carbine | - | - | - |
| Olympic Arms K4B | - | - | - |
| Olympic Arms M4 | - | - | - |
| Olympic Arms OA-93 | - | - | - |
| Ordnance SBML 2 inch Mortar | - | - | - |
| Orion Flare Gun | - | - | - |
| Orion flare gun | - | - | - |
| Ortgies 6.35mm Pocket Pistol | - | - | - |
| Ortgies Pocket Pistol | - | - | - |
| Ottoman Musket | - | - | - |
| Ottoman musket | - | - | - |
| Over and Under Rifle/Shotgun | - | - | - |
| Over and Under Shotgun | - | - | - |
| Over and under combination rifle/shotgun | - | - | - |
| Over/Under Shotgun | - | - | - |
| Owen Submachine Gun | - | - | - |