In 40k 5th edition the missile launcher was the king of long ranged anti tank. It costs a reasonable amount of points (though could vary from codex to codex) and comes with two firing flavours; krak S8 AP3 and frag S4 AP6 blast. The two different firing modes gives the missile launcher flexibility in an army and allows the unit bearing missile launchers to deal with a variety of targets.
So what has happened to the missile launcher?
Hull points - the down of mech
The missile launcher is the tag team buddy of the meltagun; the missile launcher dealt with mech at long range and the meltagun tackled mech up close. As mech has taken a tumble in 6th ed (became balanced) and hybrid lists have been introduced (half mech half infantry) then anti mech weaponry, such as the missile launcher, will decrease to match the meta game. Though you would think as the missile launcher is dual purpose it would still have a place in army lists of 6th ed.
Since the introduction of hull points vehicles can now be wrecked by causing just glancing hits. It is ultimately weight of fire which will bring down vehicles and not straight forward blunt power. The missile launcher (and it's short ranged brother the meltagun) find themselves taking a back seat to weapons which can put out volume of fire power such as the autocannon and plasma gun.
Here is example of missile launcher vs autocannon firing against a Rhino:
4 x missile launchers @ BS4 - hit 2.64 - 1.74 chance of damage - 0.27 glance 1.46 pen.
In short the missile launcher doesn't stand huge chances of taking out a vehicle in one shot. The results are not also factoring in cover saves.
4 x autocannons @ BS4 - hit 5.28 - 2.64 chance of damage - 0.42 glance 2.22 pen.
Rounding the results up the missile launcher will cause two lots worth of damage while the autocannon will cause three lots of damage; that's potential wrecked Rhino right there. In either case the AP doesn't matter of the weapons as only AP2 and AP1 have any effect on the vehicle damage chart, so really it only boils down to weight of fire.
The missile launcher does have one over on the autocannon and that is it can glance av14 and penetrate av13, though as the chances are small the autocannon will probably stand just as much chance against av13 as does the missile launcher.
But wait! There's more!
Ok, so the missile launcher has lost it's crown to the autocannon against mech. What about infantry?
The missile launcher is effective against monstrous creatures, 4 missile launchers firing krak missile would take 3 wounds off a monstrous creature without cover - though who is going to leave their monster out in the open when cover is so easy to get, just stand in a crater and kick up some dust! If the monster does have a 5+ cover then chances are the missile launcher will only cause two wounds after cover saves.
In steps the autocannon, due to the lower strength and higher AP it does struggle against big monsters and it will only cause 1.18 failed saves.
So the missile launcher takes this one. What about normal infantry? Well the missile launcher has to worry about the scatter dice, which is 33% chance to hit if I remember right and average scatter distance is 7" so minus off BS4 and you are talking a 3" scatter. The blast template is only 2.5" wide so it possible the shot may miss altogether, but it really is difficult to say as it depends how many models are in the unit and how those models are spread out.
Lets say the missile fires at 5 T4 models, hits 5 of those models twice, then another 2 after scatter and the last shot completely misses. It would cause 3.5 wounds on average and a 3+ armour save would fail 1.19 wounds.
The autocannon doesn't have to worry about scatter, though in this example would only hit 5.28, which is a little less based upon the guesstimate of the frag. Luckily the autocannon wounds a lot easier as it is S7 and would cause 1.51 failed armour saves.
Now the autocannon pulls it back and is slightly better against normal infantry.
I have the pooooooowwwwwwwwwweeeeeeerrrrrrr
Something the missile launcher can claim to is the high strength and AP. This allows it to punch through 3+ armour saves and instagib up to T4 models. The frag is also pretty handy against horde armies such as Orks and Termagants, though most weak infantry units tend to have a 5+ armour save and would be saving against the frag.
The autocannon isn't something to be sniffed at either. It has a reasonable S7 and AP4, it's like the weaker brother of the missile launcher but packs more shots in. While it cannot instagib T4 models it can put the hurt on xenos more thanks to the AP and weight of fire it has over the frag missile.
Good bye old friend
As you can see from this analysis it is no surprise the missile spam armies have died off and the autocannon now reigns in it's place. It's not like the autocannon is miles ahead of the missile launcher, it is just the fact that the autocannon can get the job done while it takes the missile launcher that little bit longer. The autocannon stands a better chance of taking out vehicles in a single volley and taking out more infantry models compared to the missile launcher when firing frag.
The missile launcher does have a few plus points and that is instagib T4 models and take wounds off monstrous creatures who have no form of cover save or 2+ armour save. Though a good player will make sure their big monster has cover from mass missile launchers and the difference in wounds between the missile launcher and autocannon is only a single wound, is that really worth complaining about?
Missile launcher, join your beloved friend the meltagun in anti tank death pool.
Do you think the missile launcher still has it's place in 40k or has it's time been and gone?