I got thinking and came to the conclusin that the Hasta is the suits equivalent of an assault rifle. There are more than that so why not enable them?
[ ] Applyied Specialisation [100]: The military has used many different weapons for many different situations. With a little work you can apply your autogun research to the wide spread classic options. (Now your Legionary can be equipped with mass accelerated shotguns, rifels, heavy mashineguns [Hasta's unwieldy big brother], sniper rifels and wrist mounted high calibers designed for them as well. GM must decide how it will impact PI. Most likly even more money and higher revenue because all the options will generate interest.)
Requirements: Compact Autogun and Wrist Mounted SMG
Why? Because those options had been developed for a reason. Adopting it for the Suits is therby fine.
[ ] Armament Downsizing [500]: Building a weapon for your Legionary was really easy. It had handeled so many things the soldiers in them could not. Like carrying the beast and providing energy. And handling racoil. Ouch. (Non-power-armor level infantry weapon of your arc reactor using weapons can be pruduced. GM must decide how it will impact PI.)
Requirements: Applyied Specialisation and Gen2 Arc and Multicore EEzo Systems
Why? Because PI is a weapon dealer. With this it would make avaible products for a really BROAD spectrum of buyers willing to pay premium. GM must say how much better (or in what regard different) they would be to standard guns. Aaaaaaand it could give the GM an excuse for not fielding OP-NPC.
[ ] Reactionary Adaption [1600]: Paragon Industries build the best. Point. This is the end-all of MA weapon engineering because
this in even more futuristic and awesome. (Imagine the weapon of the Omake with Arc technology and excess to mods. Maybe even rapidly beeing able to switch between mods [cycle through Incenedary, Charged, AP]. GM must decide how it will impact PI.)
Requirements: Armament Downsizing and Superalloys and Advanced Weapon Mods and Advanced Ammo Mods.
Why? Because super awesome gun. The Omake was just great and this is what happens if brought up to eleven. Of course the result would be big and heavy but there is Scince for that. Like a mass effect to reduce weight.
[ ] Weapon Merging [3200]: Putting together systems never meant to work together for the sake of putting them together. The result lets rocketsince look elementry. (Like above but ONE gun able to fire everything (ME sulgs, instant forged micro rockets, Repulsor, laser and whatever else. GM must decide how it will impact PI.)
Requirements: Reactionary Adaption and Gen3 Arc and Unabtanium and Transformation Systems and Particle Beams
Why? There is always something more crazy. This is the most crazy gun I could think of for this setting.