Four-forty

The colloquially named "four-forty" is an artillery piece weapon used by the UNSC Defense Force. It had been introduced recently as of October 2552. A SPARTAN-III trainee on Onyx mistook a powerful, distant explosion for the testing of a four-forty, which he claimed is a "big one"; however, whether he was referring to size, explosive yield, or both is unclear.

Type
Though Halo: Ghosts of Onyx references the weapon as a type of artillery, its name is never explained. When contacted by Halopedia, author Eric Nylund could not explain the weapon's nature to his own satisfaction. It is possible that the name is shorthand for a 4.40" (~112mm) bore, which would be appropriate for a fairly small artillery piece; however, this would conflict with Dante's description of the weapon as a "big one" unless the explosive yield is greater than the round's size would suggest. Furthermore, Nylund suggested that such a caliber is too small for his intentions. Alternately, "four-forty" may simply be a model designation such as "M440". A less likely possibility is that the four-forty is a large-scale mortar weapon, similar to Nazi Germany's 380mm Sturmtiger and 600mm Karl-Gerät.

In his response, Nylund joked that a 440mm cannon could be used against orbital targets, indicating that he did not intend for the weapon to be so large. Despite this, ground-based mass drivers of similar scale have since been introduced in Halo canon. Assuming the nickname indeed indicates a bore of 440mm, it is most likely a type of ground-based Magnetic Accelerator Cannon, though this would make the "artillery" reference a misnomer. If this were the case, the weapon's bore would be a quarter again the size of the Mark 2547 "Mini-Mac", which has a bore of 35cm and is designed to engage suborbital fortifications and vessels.

List of appearances

 * Halo: Ghosts of Onyx