There is a -1 recoil penalty to your second shot on SA weapons. In the case of the assailt cannons on SA, it is doubled if it is uncompensated, as with all heavy weapons. In the case of SS weapons, there is no recoil mod since it can't fire a second time. Where the Panther is concerned (I think that's the cannon that is SS, but they mention recoil), I assume the manufacturers made it single shot for safety reasons and to allow the weapon to cool/relax/line up the next shot.
In Arsenal, there are rules for extra recoil from heavy weapons. Honestly, I would apply those ones to the Assault cannons, but that is just me. I'm an oddball like that. IIRC, the recoil is translated to 1/2 of the weapons power in stun damage.