I view this as a long-range upgrade to the Hunchback 4G, as opposed to a customized HBK-4P Swayback, however careful monitoring of your heat gauge can let you brawl surprisingly well. The high-heat nature of these builds require not only great fire discipline, but also careful aim. It's a high-demand, but also highly-rewarding Mech. You have the choice of a more heat-efficient build with standard PPCs that are most effective to around 540m, or the hotter ERPPCs that maintain full power to about 810m out. Since normal PPCs are less effective (or ineffective) within 90m, equipping them will make you rely on the three lasers at very close range, however you'll have the equivalent of 22.5 heat sinks to keep yourself cool. The ERPPCs are effective up to point-blank, but the 3 lasers are more heat-efficient than ERPPCs. The 2x Standard PPC build offers a higher peak-damage output owing to the higher heat efficiency of Standards over ER's, and is my preferred Brawler build. I just try to keep enemies outside of 90m, and when they get too close I spam the lasers @ 16dmg per volley (not bad for backup weapons). I chose a MPL for the head because the Standard Engine allows for zombie action after losing both your arms and PPCs, and torso-mounted lasers are harder to aim than arm-mounted lasers (MPL = shorter burn than ML)... also, the high mounting placement of the head laser allows you to fire over obstacles that will block most incoming enemy fire, and the high placement of the Primary (and head) weapons is the key to the Hunchback's success on the battlefield. The ERPPC build is a good Artillery Hunter because you can engage them outside the range of their LRMs and deal about 12.5dmg/volley at ~1100m (more than a single Gauss Rifle deals at that range) from behind cover that blocks 90% of your Mech, with infinite ammo. Up close, you can use normal PPCs and outmaneuver an Atlas to continuously take pot-shots over hilltops and around corners. 2xPPC deals 20dmg faster than an AC/20 owing to the higher RoF for PPCs, but you can only dump a couple shots and then you have to run... .. but it's always in your best interests to use that 500-800 meter range in your favor to keep hotsile AC/20s and Medium Lasers from hurting you. You paid tonnage for that range, use it wisely. You also paid a high heat-price for infinite ammo, so don't worry about wasting ammo on quick/lucky shots if you're cool and not under fire.
