Topic: Ion Cannon > Railgun for anti-light vehicle/MC sniper

[Galef]

I have a friend that just got a Tau army and just got a Hammerhead.  According to conventional wisdom, the Railgun is the weapon of choice.  However, as an Eldar player that spams Scatter lasers, I see great potential for the Ion cannon.

My friend already fields 2 units of 2 Broadsides with multi-trackers (and plans of getting 1 more for each unit), so it seems he has plenty of anti-heavy tank.  But against AV 10 & 11 vehicles, the Railgun doesn't seem as appearling as the 3 shots from an Ion cannon.  In fact, an Ion cannon has a better chances of getting through any cover (or DE flickerfield) than a light vehicle might have.  Couple that with the str5 weapon options of the Hammerhead & suddenly you get a vehicle that can use ALL its weapons on its "chosen" target.

Also, the Ion cannon seems a better choice vs. Montrous creatures like Daemons & Nids.

Have I missed something?

[Wyddr]

You are correct. The Ion Cannon averages at least one damaging hit ~83% of the time against AV10 whereas the Railgun gets one ~67% of the time. It is worth noting, of course, that the Railgun *always* penetrates such vehicles and is AP1, giving it slightly greater odds to destroy said vehicles (~30% for the Ion Cannon Vs ~33% for the Railgun). The odds to destroy widen the higher the AV goes, but the Ion Cannon has pretty good odds to damage most light vehicles, often in excess of the Railgun's potential.

The Ion Cannon is, of course, better than the Railgun at damaging MCs, whereas the Railgun is far superior to the Ion Cannon when killing Infantry.   

[Kaiizen]

The problem is that there are better option out there elsewhere in our army for monstrous creatures and light vehicles. Considering crisis teams can cheaply mount twin-linked missile pods at strength 7 as well with far more shots and higher accuracy. Against monstrous creatures plasma, melta and sheer weight of fire (even standard firewarriors can do this) will bring them down.

The primary reason for taking a heavy slot as Tau is to take the weapon only available to that slot. If you don't need a railgun you should reconsider using a heavy slot at all.

[Blood Hawk]

Problem with missile pods is that they are only ap4 and most MC have a 3+ armor save.  Ioncannons, plasma and volume of fire is best way to kill MC.

[Kaiizen]

I was more referring to missile pods for light anti-vehicle than as monstrous creature killers. Against vehicles crisis teams are much more point efficient than a hammerhead with an ion cannon. They also put out a much higher volume of fire for fewer points, I don't know the numbers off the top of my head, but 6 twin-linked BS3 ap4 shots against 3 BS4 ap3 shots should actually end up with a fairly similar number of unsaved wounds.