As the French Army was relying on the OCC 105 F1[i] (obus G) as main as its only armor-piercing ammunition at that time, the rifling of CN 105 F1 gun barrel was given a relatively slow twist of one turn in 25 calibers to minimise the spin imparted to the HEAT projectile, but this made it unsuitable for firing APDS,[4] although compatible with all other types of NATO 105×617mm ammunition such as APFSDS, the OFL 105 F1 being the first French-made APFSDS and was fielded in November 1981.

[5] The CN 105 F1 is a monoblock steel 105-millimeter (4.1 in) cannon[6] protected from bending with a magnesium alloy thermal sleeve.

Unlike the similar L7 tank gun, the F1 uses a compressed air scavenging system instead of a bore evacuator.

Source:[3] A shorter barrel version designated D1504 was fitted to Israeli M51 Shermans[2] and locally known as the CN 105 D1, some of which have been sold to Chile.

In order to fit in the T23 turret of the M51, a larger muzzle brake was added to reduce the recoil length.