CN 105-57
The CN-105-57, also known as CN 105/57 or D1504, is a light French 105 mm tank gun. Design. The CN 105-57 is a light 105 mm rifled tank gun originally designed to be mounted on light tanks with oscillating turret such as the French AMX-13 and the Austrian SK-105 Kurassier. It uses the same conventional ammunition as the longer and heavier CN 105 F1 but smaller and lighter propellant charges with shorter cartridges cases enable it to be fitted into the FL 12, FL 15 and FL 20 light tanks oscillating turrets. Other changes to  the gun include a horizontal breechblock, a muzzle brake, and a single-cylinder recoil mechanism together with a single hydropneumatic recuperator. CN 105 G1. The Giat Industries 105 mm G1 is a further development of the 105 mm CN 105/57 which is installed in the French FL 12, FL 15 and FL 20 oscillating turrets. The modification enables the weapon to fire the 105 mm OFL 105 G1 APFSDS ammunition. The ordnance is fitted with a new single baffle muzzle brake, a thermal sleeve, a fume extractor and semi-automatic horizontal breech mechanism.