Ok, just finished this up, first off the 'round' above the triple barrel is the cannon round while the one below the square (the rocket launcher pod) is the RPG round. This more or less effectively turns a already Mech equiped for demolition and heavy weapon operations into an even more menacing machine. Down side is there's only four RPG rounds in the pod and they can't be reloaded while the mech is in combat, so it pushes the fact every shot needs to count.

I may see if I ever converted this weapon to a beam type weapon and add more RPG pods to the design if i did. Even if I didn't I'll likely go with the idea for the sake of giving myself something to do. The weapon is still arm mounted in case you were wondering and tactics are still as said in previous images.