Without re-checking it seems about the same as a normal cannon to me - I never really thought about whether it should be faster than that.
The description says "Instead of using gunpowder, this marvel of engineering lobs cannonballs with its powerful mechanical tentacles. It functions underwater. It also has a mind of its own, and
quickly reloads itself with anything it can find on wielder's person. Sometimes in a less-than-gentle manner; every use inflicts 6 Stun dmg."
With that description, I always took the intent of it to be that you can launch two cannonballs in a turn, in return for taking a 12 stun penalty.
Edit/Addition:
And what on earth is with these pogroms... the first two I ran into both had armored cars. Thankfully, I managed to actually succeed in both missions (technically...) with one and two civilian survivors each, and something like 30 hostiles.
At least gambling can get you early LASSes. Or a hammer/half dozen HE grenades if you're desperate. Those are the ratling/ghoul pogroms, right? At least you got some good research and car parts early.
Nope, it still can't be merciful... I have the impression I would've appreciated the early car parts a bit more if it wasn't December 7, 2601 and I
just built a Workshop... I finally got the Guild Stapler off a Guild Team Leader as the second to last thing he could've given me.