Resident Evil 4 uses a reactive ammunition drop approach. This means enemies disgorge ammunition pick-ups for weapons Leon possesses in his attache case. Ammunition for weapons not carried is reduced, or even eliminated. For the most part, you replenish ammunition after taking out enemies. You cannot buy ammo from The Merchant.
Bowgun Bolts are special explosive bolts that are used by the Bowgun. Each set of twenty takes up 4 cells (1x4) in the Attache Case.
Bowgun Bolts can be sold to the Merchant for 2500 PTAS a bolt.
Handgun Ammo is the 9MM ammunition for all handguns. Each set of fifty rounds takes up two cells in the Attache Case.
Handgun ammo can be sold to The Merchant for 50 PTAS a round.
Magnum Ammo is the .45 (and .50 for the Handcannon) ammo for all Magnums. Each set of ten rounds takes up two cells in the Attache Case.
Magnum rounds can be sold to The Merchant for 500 PTAS a round.
Mine-Darts are custom Mines for the Mine Thrower. They stick to surfaces and detonate after three seconds. Each set of five Mine-Darts takes up two cells in the Attache Case.
Mine-Darts can be sold to The Merchant for 500 PTAS a piece.