This is the first time I've used the clan uac 2 weapon system so I can't say I have a lot of experience with it. I didn't notice a whole lot of spread that couldn't be accounted for by my shaky aim
I didn't realise they had the reputation of spreading damage. What makes it different than its inner sphere counterpart (outside it being an ultra ac that can double tap and jam) that would make it spread damage though? It's not like the other clan autocannons, it only fires one pellet per trigger pull.
The IS UAC/5 is basically a normal AC that can double-tap. You fire one shell, that's five damage. You double-tap, that's ten, and so on and so forth. The Clan UACs spread their damage out across multiple shells. Take, for example, the cUAC/20, which fires four shells every time you pull the trigger. Each of those shells does five damage. What that means, obviously, is that you almost never get all the damage on a single point.
Worse still, the ammo count per ton is per shell, not per trigger pull, so you go through ammo anywhere from 2x to 4x faster than with standard cACs, depending on what size you're using.
In that respect, the cUACs are actually pretty shit compared to the IS UAC/5 (barring the fact that they can get UAC/10 and 20s), and only really good compared to cACs because they take fewer critical slots, do more cockpit shake, and can still double-tap in a sense. You get way less mileage out of each ton of ammo, spread your damage a lot more, and have to deal with jam chance. They're mainly viable for Clan dakka builds because of the lower cooldown and better blindness/shake working well for brawling, you can cram more into slot-limited omnimechs, and because (IIRC) each shell has independent crit chance.