Showing 34 of 34 firearms starting with "O"
| Name | Manufacturer | Caliber | Type |
|---|---|---|---|
| O/U Combination Gun | - | - | - |
| O/U Shotgun | - | - | - |
| O/U shotgun | - | - | 12 Gauge Double Barreled Shotgun |
| OA-93 | - | - | Olympic Arms OA-93 |
| OF 37 hand grenade | - | - | - |
| OICW | - | - | Heckler & Koch XM29 Objective Individual Combat Weapon |
| OP-SKS | - | - | SKS rifle |
| OP-SKS Rifle | - | - | - |
| OSP-30 | - | - | OSP-30 Flare Pistol |
| OSP-30 Flare Pistol | - | - | - |
| OSS Pistol Glove | - | - | Sedgley Fist Gun |
| OSSh-42 Flare Pistol | - | - | - |
| Oberndorf Mauser Sporter | - | - | Mauser Rifle Series |
| Oerlikon 20 mm Cannon | - | - | Oerlikon 20mm Cannon |
| Oerlikon 20mm Cannon | - | - | - |
| Olympic Arms CAR-AR | - | - | - |
| Olympic Arms K23B | - | - | - |
| Olympic Arms K23B Tactical | - | - | M16 rifle series |
| Olympic Arms K3B Carbine | - | - | M16 rifle series |
| Olympic Arms K4B | - | - | M16 rifle series |
| Olympic Arms M4 | - | - | M16 rifle series |
| Olympic Arms OA-93 | - | - | - |
| Ordnance SBML 2 inch Mortar | - | - | - |
| Orion Flare Gun | - | - | - |
| Orion flare gun | - | - | Orion Flare Gun |
| Ortgies 6.35mm Pocket Pistol | - | - | Ortgies Pocket Pistol |
| Ortgies Pocket Pistol | - | - | - |
| Ottoman Musket | - | - | Jezail Musket |
| Ottoman musket | - | - | Jezail Musket |
| Over and Under Rifle/Shotgun | - | - | - |
| Over and Under Shotgun | - | - | 12 Gauge Double Barreled Shotgun |
| Over and under combination rifle/shotgun | - | - | - |
| Over/Under Shotgun | - | - | 12 Gauge Double Barreled Shotgun |
| Owen Submachine Gun | - | - | - |