The weapons factory is a location in Jak II. It is an industrial factory outside of Haven City situated north of the Pumping Station and near the Dig Site. It is here where the Krimzon Guard produced their weaponry, including Krew's Piercer Bomb and the prototype for the KG Death Bots.
Jak, with help from Ashelin Praxis, managed to enter the weapons factory where he intended to interrupt a meeting between Krew and Baron Praxis. He received heavy resistance while in the factory, defeating the biggest amount of Guard and Elite Guards so far and destroying several of the early prototype KG Death Bots later seen in Jak 3. He eventually managed to reach the top where he encountered Krew. After the fight Jak retrieved the Heart of Mar from Krew, who detonated the Piercer Bomb.
However, Ashelin managed to rescue Jak and Daxter, and they escaped while Krew died in the ensuing explosion.
The lower levels of the factory can be accessed after this but the upper ones are blocked off.
The Weapons Factory a top-secret area where the Krimzon Guard developed various weapons to fight the Metal-Heads, and requires black-security clearance to enter. The facility is protected by Krimzon Guards and the UB-86 robots, predecessors to the KG Death-Bots in Jak 3.
Most of the facility is filled with conveyor belts and radioactive waste, though no one has been very affected for unknown reasons. The facility is primarily a large tower that is comparable in size to the Haven Palace, though all but the base was destroyed when Krew detonated the first Piercer Bomb on top of it, but the Baron kept a copy of it at the Construction Site. It was still standing later in Jak II. The place where you defeat Krew was blown up by the Piercer Bomb and cannot be revisited.
The weapons factory contains five Precursor orbs, all of which can be obtained during the factory's lone mission Get Heart of Mar in Weapons Lab or any subsequent visit.