Scrub is armed emtirely with energy weapons. I don't think the Locust has the weight/space to allocate a PPC of any kind and still support the ranges (both short) and damage values that it carries.
The real threat of the mech seems to be the secondary weapon slot that shows Pulse SE. It also hase Evade, that helps to get it quickly into position and adds a bonus to defense.
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My guess is that it packs as many ER Small Lasers as it can, with an option to carry a set of ER Medium Lasers, though a 10 inch range doesn't seem to agree with that. Pulse SE is not actually a battery of rapid fire weapons, but rather a system of using only half the available energy weapons to avoid overheating while engaging the target.
GC