Since open beta started I have kept a PPC/ERPPC based Catapult K2 and have played on a fairly regular basis. I've seen others who pilot similar 'mechs struggle, so I'm putting this guide together to aid anyone else who stuck it out with PPCs. If anyone else has any additional points to add, please comment below.
The Build:
Early: When you first get this mech you will likely find it to be disappointing, especially when it comes to heat efficiency. To help with this early and cheaply, drop the machine guns and ammo to add two more heat sinks.
Late: Once you have the C-bills upgrade to double heat sinks and place them where-ever you have room. This will allow for a much more sustainable rate of fire, and gives you the heat dissipation to use ERPPCs instead of PPCs. If you have weight left over (I did) the two best upgrades are speed and AMS. Pre-ECM I would have prioritized AMS because this design should spend most of its time at long range. With ECM as it is now, either choice is just as valid, since you should be spending most of your time outside of the ECM bubble, but LRMs are far less common. Speed is always use full, but I would recommend staying away from XL engines right now, since many target the side torsos expecting that you are carrying Gauss Rifles. This will likely pass with the coming PPC buffs as people learn to recognize the different arm barrels.
Weapon Grouping: I keep my left PPC on the left mouse button, and the right PPC on the right, with the medium lasers on my third mouse fire button (varies by mouse). This makes firing around corners intuitive while making alpha strike or ripple fire both easy to do.
Strategy: (Note that if you still have PPCs instead of ERPPCs that you will lose damage if the enemy is within 90m, with more loss the closer they are.)
First off, keep your distance, and if you can't see the enemy try using thermal vision (H by default). Even the standard PPC has a rather long effective range, and can still do slight amounts of damage out to rather extreme ranges. The ERPPC is even better at extreme ranges. Typically on the current maps if you can see it, chances are good that the ERPPC can do at least slight damage and rock them, making it harder for them to counter.
At long range only fire both PPCs simultaneously if you can guarantee a hit. Instead ripple fire them. This will increase the chances of getting hits, keeps the enemy disrupted by rocking, and makes it easier to manage your heat. When skirmishing in the manner it is important to keep your heat low (preferably below 50%) so you can effectively defend yourself if you get jumped by a mech at close range, but don't be afraid to keep taking shots. You don't have to worry about ammunition like most sniper builds do.
At medium range the same principles apply, but if you see an easy target it becomes worth it to raise your heat and fire both PPCs into weak spots.
At close range things change. If you are facing a slow mech use only PPCs until they get too close (about 75m with standard PPCs and 10m with ERPPCs due to limited convergence from the arms). If they get closer then that switch to a steady firing of your medium lasers while you try to regain that distance.
(ERPPCs can be effective at closer ranges by aiming past the enemy so that they are in line with your arm, then aiming on the other side of them with your other arm.)
When fighting close up with a fast much only use PPCs if they are stopped (for any reason). If they are moving stick with the medium lasers. If you can, leg them so you can bring your PPCs to bear. Don't expect to be able to take a good light pilot 1 on 1, but don't give up either. If they make the mistake of stopping for just a moment those PPCs (ready to fire because you have only been using medium lasers) came do a lot of damage to their leg, and a legged light is an easy kill for this build.
Notice how high the Catapults arms are? Means that you can crest a hill just enough to see the enemy and start firing those PPCs while remaining mostly in cover.
If you find yourself overheating attempt to break contact. This is where any extra speed you may have can come in handy. Once you cool down reinitiate contact with a full out assault.
With the coming changes to the PPC and ERPPC this design will become even more effective.
If you have any further points please place them in the comments.
Edited by RobarGK, 11 December 2012 - 11:03 AM.