My current list utilizes shooty Riggers to maximum effect:
Endrinmaster with dirigible suit general
1x ironclad w/volleygun
1x gunhauler w/drill cannon
1x5 Thunderers w/ rifles
10x3 Endrinriggers w/volleyguns & drill cannons
I start the Thunderers inside the ironclad, and keep the general and 2 units of riggers close enough to repair and hitch
I keep the gunhauler close enough to help defend the ironclad and give it 2 units of riggers as well, close enough to repair either Skyvessel.
the remaining 6 units of Endrinriggers spread out, claim objectives, shoot at enemies, and relieve repair duty if one of those units hitching skyvessels is weakened.
so I have a total of 10 ‘drill launcher’ attacks that do 3 mortal wounds on a 6 to hit at 24” away, or do 4/3/-3/d3 otherwise. Great for targeting heroes and high priority spell casters.
Volleyguns are pretty good too, especially against low armored horde type units.
That’s 60 shots at 4/4/-1/1 also from 24” away. Rivet guns are the weakest link, but 30 shots at 3/4/-1/1 is a good little boost when enemies are in range.
so altogether my Endrinrigger’s shooting has a potential damage output of 120 per turn, averaging around 31 damage per turn if everything shoots. Since I have the mobility to pick and choose my targets, I think that’s really good.
When I add my general, ironclad, gunhauler, and Thunderers to that and my shooting has 201 potential wounds per turn, or about 59 wounds on average (before saves).
Defensive placement, priority targeting, and wise use of rerolls can make for a devastating hail of gun shots... and repair up to 34 damage per turn.