I may be reading this wrong, but are the 4.2" rockets stats meant to be read in the following manner?

fire 1 rocket use 3/1, fire 4 rockets use 12/1?

Cannot seem to find anything similar to it's profile in the rulebook.

Thanks.

Now to figure out where I can find some metal strips for the thing.. that turret sure wont stay put

Yep, that's it. It's called a Volley Blast weapon.

Thanks, was not sure