How does it work?

Full-Auto says that it takes a full-action to fire and that it's possible to fire two weapons at the same time (one in each hand).

Thous would mean that you can fire a full-auto burst with two pistols in a dual shot. Is this correct?

If you roll good with a auto-pistol you can get 6 shots (average) to hit that meaning you dealing 6d10+12 in wounds only subtracting the toughness once. If you get a better weapon (say a bolter) or better amm. with armour penetration everything would hit home. Nothing survies that. especially not the acolytes...

We got into this discussion when we realised that Slaught in Dark Disciples had 10 toughness but no armour. He wouldn't stand a chance against a acolyte armed with dual shot and full-auto.

Have we missed anything or are the rules just broken?

Dual shot gives you one single shot with each pistol. “Armour gets applied as normal to both hits individually, but Toughness only counts once against the combined damage rolls of both hits.”

So against your Slaught target your damage from both pistols is combined and then the TB is applied before wounds taken are calculated. Even single shot this is a very nasty talent against unarmored opponents.

No, because full-auto is a full action and dual shot is a full action. You can only take a single full action in a round. As ItsUncertainWho said, Dual shot talent allows a single shot from each weapon to combine into a single shot overall. Instead of subtracting Toughness form each shot, you add the two weapon's damages together and subtract the Toughness only once.

As people have already said, the special Dual Shot cannot be used with full-auto fire. You'll still be able to damage the Slaught with Dual Shot though, on average (even with autopistols) and it's probably worth it to use it rather than just firing both guns on full auto.

Friend of the Dork said:

What he said heh. Dual shot is often the best hope of doing damage to some of the seariously tough enemies out there if you don't have access to heavy weapons or anything beyond las and sp.