My gunners always have heatsink on stuff for gunners where engineers are not always available to help, like a Mobula, on a Pyramidion though, the balloon engineer can fix most fires on the gunners gun. Also that decreased arming time is similar to greased and works decently as an alternitive to greased when enemy is going close range against your Hades Pyramidion or when they are one the wrong side of your average "long range one side and close range other side"-Galleon, so you can use Lumberjack inside arming time a little bit better and have fire protection.
The rare moments where I have my non-gunner crewmembers bring heatsink, because it is important for the setup, is when we bring this Hades/Mercury Pyramidion and I put the engineer on the Mercury with heatsinkt to snipe the primary guns of the enemy, like the front guns of a Pyramidion and Goldfish, with JarmenKell shooting that Mercury it is pretty neat. Another time for my crew to bring heatsink would be for the light Flak that the hull engineer shoots on some spire build.
Another thing where I have my non-gunner crewmembers use heatsink is on stuff they don't use often themselves, like the Pyramidion's side gun. When it comes down to it, heatsink will be there.
Heatsink doesn't turn guns into dps beasts like greased does, but it is a great utility ammo type.
