Which component among the following is NOT a major part of the M119A3?

The reason the firing pin is not considered a major part of the M119A3 is because it is a specific component that contributes to the operation of the breech mechanism rather than being a standalone major assembly. The firing pin is a smaller part that plays a crucial role in initiating the cartridge's ignition but does not constitute a major structural or mechanical element of the artillery system.

In contrast, the recoil mechanism, breech mechanism, and cannon cradle assembly are significant components that contribute to the overall function and operation of the M119A3. The recoil mechanism is essential for absorbing the energy produced when the weapon is fired, allowing for effective operation and firing without damaging the gun. The breech mechanism is responsible for loading and securing the ammunition, ensuring safe and reliable firing. The cannon cradle assembly supports the cannon tube and allows for elevation and traverse, which are critical for targeting and firing accuracy. Thus, these components are integral to the artillery piece's function, while the firing pin serves more as a supplementary function within the broader mechanisms at play.