As new Elite Dangerous players delve deeper into starship engineering, questions about the corrosive shell effect always come up. It’s one of the best weapon effects, but it’s not as obvious to use as “increase damage/range by X%” modifications. Here’s what the wiki has to say about it:
Corrosive Shell is an Experimental Effect that can be applied to a weapon through Engineering. It consists of experimental rounds that temporarily weaken Armour Hardness and increase all damage taken, at the cost of a 20% reduction in ammo capacity. While the effect is active, incoming damage from all sources is increased by 25%, and all attacks receive a +20 bonus to their armour piercing value.
The effects of Corrosive Shell do not stack on a single target, and therefore it is most efficient and cost-effective to only apply it to one weapon per ship. Furthermore, the type and size of the chosen weapon does not alter how the effect is applied or its duration.
https://elite-dangerous.fandom.com/wiki/Corrosive_Shell
The corrosive shell effect reduces armor hardness which improves the damage smaller weapons have on larger ships. AND it increases ALL incoming damage by a hefty amount. Good to know, but there are a few finer points to consider beyond this conventional wisdom.
First, I don’t agree with “one weapon per ship”: you need one weapon with the effect that can hit the target reliably. I often put it on a ship’s two smallest hardpoints, particularly for ships where I cannot always guarantee that a single corrosified hardpoint will completely cover my main weapons’ firing arcs–I’m looking at you Imperial Cutter wingtip hardpoints! OK, and I also have an obsession with symmetry and knowing mirror hard points have different engineering or even–gasp!–different weapons in them drives me to distraction.
Second, the effect has a duration, so you only need to tap the target to apply the corrosive effect. You can see if it’s applied along the bottom of your target in the Ship Status Indicator. (I did see a mention on reddit that the bottom bars might be progress indicators which would be very helpful, but I haven’t confirmed this.)
Third, pay attention to your ammo levels. The High Capacity Modification is the best engineering modification to put corrosive shell on top of; it will more-than-compensate for the 20% decrease in ammo from adding the effect to a weapon. Even so, be careful not to burn through your corrosive ammunition too quickly. If they’re running dry before your main weapons–or if you’re supplementing a laser build–then you may want to keep corrosive weapons on a separate trigger and only use them when the target doesn’t have the effect and is shieldless. I usually group them with other cannons or hull-based weapons, then alternate fire with my non-hull weapons since they also benefit from the corrosive effect on the target.
Corrosive Shell is a great experimental effect overall, and it’s particularly handy for smaller ships or smaller hardpoints attacking larger targets. I hope this helps you get the most out of this trip to the engineer since it can only be applied in person, not pinned. Maybe the fourth point is to engineer a few extra class 1 and 2 weapons when you’re there so you don’t have to keep going back to “The Blaster“.
Fly corrosively, commanders!