While most discussion of Tau tank weaponry revolves around comparing the Hammerhead’s railgun and ion cannon options, as well as the Skyray’s seeker missiles, the secondary weapon options should not be overlooked. While there are three options – dual burst cannons, smart missile systems, and paired gun drones – only the first two come into play for our heavy support choices*. So, which is better, either in general or situationally?

At first glance, the dual burst cannons seem to be a very solid option. For half the cost of the SMS, you get half again as many shots, all with the same strength and armor penetration, that can be split evenly between two separate targets. You do lose 6 inches of range, but it seems to be a fair trade for what you gain. More fire is always better, right?

However, the extra 10 points spent on the SMS gets you more than just extended range. Just what do you get for the extra cost?

1. 6 extra inches of range. More reach is always good, especially if it can soften up or eliminate a unit before it gets into assault range.
2. Ignoring line of sight. This alone is worth the extra points. Being able to hit anything in a 24″ radius, regardless of whether it’s hidden behind a hill, wall, or another larger unit (like a vehicle) is invaluable. It allows you to remain a threat while removing the need to expose yourself to the target.
3. Ignoring many cover saves. In the cover-save-rich environment of 5th Edition, this is huge. The SMS ignores any cover that the target is not inside (area terrain) or touching. This allows you to ignore intervening units (either your own or your opponent’s), as well as most terrain between the tank and the target. Also, with the rules on whether a unit is in cover or not, half the targeted unit would actually have to be touching its piece of cover before it would gain any benefit.

The SMS has some major adavantages that the dual burst cannon just can’t match. However, that doesn’t mean that the missiles are superior in every way to to the cannons. First, you do give up some killing power with the SMS. Over a standard 5 turn game, the burst cannons can potentially have 10 more shots than the smart missiles. Against a lightly-armored army like Orks or Eldar, that’s likely to be as many as 5 to 8 additional kills. Second, while cover saves are great, they’re not going to matter much against an opponent with heavier armor. Space Marines and their equivalents will get their armor save against both AP 5 weapons, so ignoring cover saves may not make as much difference as one would like. Finally, 10 points less is 10 points less; if you need to shave points off of your army list, downgrading from an SMS to dual burst cannons is a viable option.

There’s also an additional caveat on both of these weapons – the usefulness of both is highly limited without the additional purchase of a target lock. Without that upgrade, these weapons are limited to targeting the same unit as the vehicle’s main gun. For a Hammerhead with an ion cannon, it’s an annoyance; for one with a railgun, it can render the secondary gun(s) useless. In most cases, you’re going to want to take the target lock, so just figure that into the vehicle’s true cost (unless, as mentioned, you’re running an Ionhead and don’t care about splitting fire). The Skyray has an advantage in this case; it comes already equipped with a target lock, so it ignores this issue completely.

Speaking of the Skyray, it approaches the choice of secondary weaponry from a completely different angle. Its primary armament – the two networked markerlights – have no strength, making them defensive weapons. That means that whatever you choose for the front turrets become’s the Skyray’s main gun, thanks to 5th Edition’s more restrictive defensive weapon rules. With that in mind, the single SMS is a better choice than the dual burst cannons. A Skyray with an SMS can move at combat speed and still fire all its weaponry, all without the need of a vehicle multi-tracker; with the multi-tracker, it can do the same at cruising speed. The burst cannons, on the other hand, would lose half their shots, as only one would be able to fire.

So where does that leave us? In many ways, the SMS is the superior option for our heavy tanks. With its ability to ignore most of the things that would prevent you from targeting another unit and landing hits, it’s a great option that’s well worth the points. That doesn’t mean that the burst cannons are bad; they are still a viable, and significantly cheaper, option that has similar killing effectiveness. In the end, if you have the points to spare, go SMS. If not, don’t be afraid of going with option #2.

* Gun drones have weaker weaponry, don’t benefit from a targeting array, and give up more kill points, all for the same cost as the SMS. They’re not even remotely viable as a useful option for our tanks.