AMM vs. beam defense

[Nightstar (OP)]

I finally got around to building a more standard missile fleet. I put in AMMs as that's what everyone uses. Because I'm me, I ran numbers to figure out what they could stop. To my utter surprise, AMM based defense was less than twice as good than the beam based I'd been using, per cost. After factoring in the missile costs, AMM defense in a single prolonged engagement cost practically as much.

On the positive side: AMMs have the advantage of only needing a little tech you didn't already buy for missiles. AMM ships should get obsolete slower with new missiles. IIRC AMMs also get better at higher tech levels.

I'm still kinda shocked.

What have your experiences on beam vs. AMM active defense been? Which do you use and why?

[CheaterEater]

I use all three, AMMs, gauss and lasers. AMMs are nice because of their range; I shoot for a 3 mkm range with my AMMs. It needs a larger investment in FCs and missile sensors, but pays off (I feel) in how many salvos I spend per missile. It's also a good last-ditch weapon as it vastly outranges beams, making it good for hitting smaller craft or sandpapering enemy armor to prep for close combat. Gauss cannons spit out a lot of rounds very cheaply making them very, very good against large missile swarms. So AMMs can deal with larger missiles, gauss take care of missile swarms and leakers. Lasers then are dual-purpose, even the smaller sizes can dish out a ton of damage at JPs or any other close-range scenario. When they aren't nailing enemy ships they're good area-defense weapons. They're also better against armored missiles.

[Bremen]

In theory, AMMs should have increased effectiveness against reduced fire rate launchers. If enemy ships are spitting out 8 missiles every 10 seconds, then they could eventually overwhelm your AMMs by giving them too many targets to shoot at, but a gauss based PD system will fire on every one of those 8 missile salvos. On the other hand, if the enemy launches 24 every five minutes, then the AMMs will get a lot of shots off but gauss only gets one.

Also, as mentioned, AMMs can make a surprisingly nasty secondary weapon system. If you're engaging enemy ships with gauss PD then it's probably an act of sheer desperation.

[TheDeadlyShoe]

AMMs - coupled with strong sensors - are the only way to have a prayer of stopping box launch salvos.

[Nightstar (OP)]

Mmm.  A bunch of people that refuse to use size 1 ASMs use AMMs, so I assumed there was more to it than offensive potential.

The advantage of AMMs against reduced size stuff only comes into play with extra large sensors and fire controls, which are expensive to begin with.

Good enough reasons I guess, but I think I'll stick with my railguns.

[metalax]

I've always found a combined approach works best.

AMM's are fired first to thin out incoming salvoes, typically only one AMM for each incoming missile. This reduces the amount of ordnance expended in each battle, compared to trying to use just AMM's for defence.

Laser PD is used to further thin out incoming salvoes at range, and also helps to deal with any armoured missiles.

Finally gauss turrets are used in final fire to deal with the remaining missiles. The shields mounted on my ships are usually sufficient to deal with the few leaker's without suffering actual damage.

[CheaterEater]

I'll add a few things on gauss cannons. You need a decent fire rate tech before they become useful, I don't start using them until at least RoF 3. At RoF 4 they become much better and only scale up from there. Railguns are good at lower tech levels because they start with more shots but you can turret gauss cannons, making them significantly better against faster missiles. I use reduced size gauss cannons (half size) which allows me to make smaller turrets which I can throw onto ships that have extra space. The fire controls don't take up much and even pretty basic sensors will work. They're hampered significantly by armored missiles and ECM, but AMMs aren't hurt by ECM much and lasers (some people use meson turrets) work against armored missiles. So they make a very poor single-line defense, if I were limited to only one type I would not be using gauss. However, they are much better in larger fleet operations where dedicated gauss-pd escorts can support other ships and also better for economic reasons.

If I had only one choice it would be AMMs because they're the most effective even if they're expensive. Beam pds very much depend on having pd superiority over their missiles. If you ever run into a fleet that can out-do your beam pd it's going to start blowing up ships very quickly if that's all you have. On the other hand AMMs can stop more but they're going to burn through your missiles faster. In effect, with AMMs you can trade off magazine space to deal with more missiles but with beam pd you can only trade off armor and eventually ships.

[Jorgen_CAB]

I have found out that using about 1/3 gauss, 1/3 laser and 1/3 AMM is a very good mix.

Beam PD is used if I have PD superiority and AMM gets involved against large salvoes to reduce them to a level for beam pd to deal with them. Over time I normally calculate that I actually can afford 2-3 beam PD for every AMM ship that I deploy so in industrial cost I dedicate about 50% into AMM and 50% into beam PD ships.

[Icecoon]

If you're engaging enemy ships with gauss PD then it's probably an act of sheer desperation.

Happened for me when fighting swarm soldiers. Actually the ones with more range are pretty good against them.

...

To the topic... In my multi-empire start game one faction uses shields and meson turrets for missile defense and the other race uses only AAM and CIWS. The first faction lost none of their ships, the second lost all of them.

[SteelChicken]

As others have said, layers.

AMM's  (only used for massive salvoes)
Lasers
Gauss
CIWS
Shields