Charge the Core by dismantling 10 Rare or higher quality Fusion Rifles.
Return the Prototype to the Gunsmith.
Flavor text
"This design is new to me, but the components required for its construction aren't. This Core absorbs the energies of dismantled weapons. Take it, charge it, then return it to me."
The weapon is nearly ready. Bring the Prototype to the Gunsmith to detach the sensor.