What do you guys think is the caliber of the Sutherland's standard machine-pistol?
Judging by the relative small size of the KMF, their seeming ability to resist most weapons mounted on light armored vehicles, and the machine-pistol's ability to tear up another Sutherland, I'd say it was 25, maybe 30mm.
The closest real world equivalent may be the compact 30 x 113mm round used on Apaches, to save weight and size and all that.
http://www.fas.org/man/dod-101/sys/ac/equip/m230.htm