Fallout: New Vegas ammunition

Ammo boxes
¹ Compatiable with .357 Magnum rounds.

Ammunition Mechanics
The damage dealt with a certain ammunition type is calculated as follows (the final calculated value is scaled with game difficulty, e.g. at very hard only half damage is dealt).

damage = (base_damage - target_DT) * damage_multiplier

base_damage is the damage shown in the Pip Boy with standard ammunition loaded. target_DT is the targets armor rating, potentially reduced by a flat amount (armor piercing ammo) or multiplied by some value (hollow point ammo).

This calculation means, the ammunition damage multiplier is only applied to the part of the damage that goes through the armor (and consequently, hollow point ammo performs poorly, if the target is even lightly armored).

If the calculated damage is less than 20% of the base_damage, 20% of the base damage is dealt (any damage is not applied).

If an attack is a critical hit (including sneak criticals), target_DT is completely bypassed (if base_damage is more than target_DT) and 2x damage (normal critical hit) or 4x damage (sneak critical) is dealt.

Head shots multiply the damage result by 2 (resulting in a 4x damage multiplier for normal criticals and 8x damage multiplier for sneak criticals). Armor is only bypassed/reduced for critical hits.

Notable Vendors
These are vendors carrying large amounts of certain ammunition types.


 * .308: Daniel Contreras at Camp McCarran
 * 12.7mm: Daniel Contreras at Camp McCarran
 * 12 gauge shotgun shell: Quartermaster Bardon at Hoover Dam
 * 25mm grenade: Gun Runners (Vendortron and Alexander)
 * 40mm grenade: only available in very small quantities (Gun Runners, Ammunition Vendor at Nellis Air Force Base)
 * Flamer Fuel: Chet at Goodsprings, Johnson Nash at Primm

Bugs

 * Ammo boxes: If the item was purchased through a vendor, the player may have to drop the ammo box onto the ground (through the Pip-Boy) and pick it up off the ground to receive the ammunition contained inside the box. *Confirmed*
 * Occasionally when switching between types of ammunition for a gun, the loaded ammo may become "stuck" and not allow you to switch. To correct this, drop all ammo of the currently loaded type. The gun should then switch to the other ammo type and you can pick the first set of ammo back up. *Confirmed*
 * When using ammo that modifies a weapons damage, all viewed weapons show equally modified damage regardless if they can even use the ammo. Using ammo that does 1.5x damage will show a grenade doing 1.5x damage on mouse over.