Just spitballing here:
Let's say a Rigger has the aforementioned Steel Lynx Combat Drone, which can hold 4 weapon mounts. (Jesus this thing has 16 armor too!)
If they put a Yamaha Raiden in each slot (since it's a rifle, I believe the rules say you can slot up to an Assault Rifle with 250 rounds), each gun attacking by itself would have AR 11 (at Near Range) + Sensor 4 (of the Drone) for a 15 dice pool if one of them shoots.
Now let's say I followed the Multiple Attack rules for shooting all four in one go by commanding the drone to attack. Lowest firing setting is SA, semi-auto which I believe fires two shots, decreasing AR by 2 and increasing Damage by 1.
So now we've got AR 9 + Sensor 4 for each gun at a DV of 5. I would think you take each pool of (now 13) dice and divide it by 4 attacks for 3 dice in each pool, however any of those that hit will do 5+[net hits] of damage, which is ridiculous, but would only really have a chance on Prof rating 2ish and below.
If anyone sees anything completely wrong with that or has anything add I'd appreciate it. Doesn't really seem that good and you'd be better off as a Rigger having one or two guns per drone.