First up then, let's look at the basic centurion, who comes equipped with a pair of twin linked heavy bolters and a hurricane bolter. Quite clearly this guy is focused on an anti infantry role, and with three shots at 3' range, increasing to 6 at 2' range and 9 at 1' range, charging him is akin to walking into the proverbial storm of fire, especially since the minimum unit size triples those numbers. Going deeper than that however, we need to remember that generally armies of that type tend to have lots of bodies in them, and I'd have preferred to see two separate heavy bolters rather than the twin linked version. That being said however, 9 twin linked heavy bolter shots should result in 8 hits, which against most armies of this type will translate to 5-7 wounds, and kills providing they're not receiving a cover save. Whilst this is unlikely to make either orcs or tyranids flinch, if you then add in another 4 wounds from the hurricane bolters at 12-24" range, you start doing some more significant damage.
I think the biggest problem with this load out therefore is that for what it achieves, the points cost you pay for the squad is quite high, and against transports the heavy bolters aren't likely to be able to punch through their armour.
A second option therefore for the dakka centurion would be to take missile launchers in the chest plate. The krak missiles will provide a certain amount of anti transport fire, and the frag option is not only usable at a greater range than the hurricane bolter, but can potentially hit more targets.
This would probably therefore be my preferred load for a dakka centurion, giving them a serious amount of anti infantry firepower whilst retaining a mid-level anti transport threat should your opponent decide to bring lots of vehicles.
The next weapon option therefore is the grav cannon and grav amp, and this seems to generally be the popular choice for equipping the centurions on the various internet forums.
Let’s start with range, as it’s the grav cannon’s greatest drawback. 24”. That’s right, get this baby into range and just about every weapon in your opponent’s army will also be able to fire back at you. This makes positioning the centurion key, as you want to be able to keep just the target unit in range, hopefully wiping it out before it gets the chance to return fire and preventing anything else from ganging up on you. Centurions are tough, no doubt, but when sporting grav cannons against power armour and above, they’re going to be targeted with everything your opponent has, and that 2+ save and 2W won’t stop a very expensive unit from being flattened if they become the sole subject of attention. Added to that, they’re not a cheap unit so you can’t even dismiss it on the basis of spending an entire turn shooting at a minor part of your army, since in a 1500 list, they’re likely to be around a third of your points. That’s where their lack of manoeuvrability also hinders them however, since the lack of a realistic transport option means you don’t want them stranded on a flank too much.
With the grav cannon, I’d say that it really doesn’t matter which option you take for the chest system, as both provide decent benefits. If I were writing an all-comers list I’d probably take the missile launchers, to allow use of the frag missiles from range against lightly armoured hordes, as this is where the grav cannon falls down in my estimation (though the grav amp does help a little in this regard). Hurricane bolters would be decent, but your average space marine army really isn’t short of bolter fire.
Lastly therefore we have the lascannon variant. Three twin linked lascannons can put a dent in almost anything, with only landraider equivalents really being able to survive reliably (that’s what melta weapons are for). Even so, three twin linked lascannons stand a decent chance of penetrating even a land raider’s hull, particularly if you are using the Imperial Fists chapter tactics. This variant is to my mind the one that leaves the centurions where they should be – well back in your deployment zone to minimise the amount of return fire, bringing down enemy vehicles at their leisure, with your opponent not sure whether to concentrate their fire on them, or the other units that are threatening their own lines. Added to that, the centurions pack missile launchers (hurricane bolters would only be useful to this loadout as a defence mechanism against deep striking units), which only multiply that firepower against vehicles and provide redundancy against hordes. The missile launchers also provide a decent defence, as let’s remember that if a unit is deep striking it has to wait a turn before it can charge you, giving you a chance to train your guns and have a round of shooting first.
So in conclusion:
Dakka centurions – decent anti-horde firepower but that’s something marines aren’t short of elsewhere for less points.
Grav centurions – excellent against an armoured foe and the plethora of Riptides et al you see around, but quite situational and difficult to use properly.
Las centurions – very expensive, but range can be used to minimise return fire and keep other units higher in your opponents priority list.
You thought I’d forgotten didn’t you, there’s one more toy the centurions bring to the party. The Omniscope. What this does is give the sergeant the night vision and split fire rules, allowing you to focus on two separate targets each turn. This complicates our analysis further but let’s just pick up a couple of important points first.
Split fire does not allow you to break open a transport and then fire the remaining weapons at the unit from inside it (essentially, the shots are considered to be taken simultaneously)
Night vision confers this rule to the whole unit, not just the sergeant, so you can fire all those lascannons at full effect even in the dark.
Right, so that’s those points out of the way, what options do we have for using the omniscope.
Dakka centurions. You’re probably not going to want to fire dakka weapons at two different squads, so you’re looking at either a grav cannon or lascannon sergeant. The lascannon is solely anti tank and so would only benefit if there were a lot of transports facing you, and the grav cannon is best against heavy infantry. Bear in mind however that in a squad with a character leader (say for example Nobz in a boyz mob) if the sergeant has the grav cannon, he can roll precision shots and apply those to the nob. Keep the missile launchers for longer range shooting and you’ve just increased the effectiveness of the unit at taking down the tough stuff without hurting its ranged effectiveness too much.
Grav centurions. As noted earlier, these guys are immensely situational anyway given the way they wound, their biggest problems being lightly armoured infantry. What I can’t see however is that taking out a grav cannon and giving them a single heavy bolter option is going to significantly improve things. Where I could see a use would be in taking a lascannon for dealing with armoured transports. The question however becomes is it better to take a twin lascannon or rely on the massed dice of the grav cannon to glance a transport to death. Using a mono-weapon split fire is a viable option however, as the high number of shots from a grav cannon means even a single one can be a threat to heavily armoured troops.
Las centurions. You’ve probably already realised this is my favourite loadout, and splitting that lascannon fire is great in my book, it gets a re-roll to hit from being twin linked anyway, and with the right chapter tactics, gets a re-roll to penetrate too. In my book, taking down potentially two tanks in a turn is a very good thing, and this is definitely going to be the default armament for my guys. Considering the other options however, both the grav cannon and heavy bolter options target alternative unit types to the lascannons, and I can certainly see the argument that either of these provides security against deep striking units dependant on your opponent without detracting substantially from the unit’s firepower (really, two lascannons should be enough to kill most things). My own opinion on that matter however is that you take centurions to kill targets, if you’re worried about them being charged or ambushed then leave a unit behind to protect them, don’t compromise your weapon loadout just in case your opponent tries to get them (seriously, you should always leave something nasty in your deployment zone to deal with enemy units trying to get linebreaker anyway, and the bottom line is that centurions are unlikely to survive the entire game since your opponent won’t like them much).
So there you have it, centurions, in a nut shell (well, whacking great suitcase). As always feel free to leave a comment if you have any ideas I’ve missed.