A possible concept is some combination of coil gun with conventional powder, said powder's rate of burn accelerated electrically. You have the turret to play with but if you remove personell from the turret you need to find alternatives for those personell or alternate space to put them.
To start with - what kind of power could a coil gun of this size produce?
Originally posted by GastelDude, we'd be feeding the masses. Both candy and manflesh!
And now you've made jelly beans an ordnance. Is there anything sacred to you ATY? Please think of the children and how tormented they would be to see their families and villages wiped out by wave after wave of jelly bean ordnance. This is just too cruel to contemplate!