Manufactures projectile ammunition used by cannons and railguns. Consumes Sulfur. Gains +25% production speed for each adjacent factory of any type.
The Cannon Ammo Factory is a factory part that consumes Sulfur to produce Ammo. It gains a +25% production rate bonus when adjacent to another factory of any type.
The value of the produced Ammo is double that of the required Sulfur, allowing for an easy profit.
Logistics
You also get more benefit per tile of ship space used by going for a factory setup instead of storage, as you can see below. It takes more crew and needs energy however.