Junk Rounds

Junk Rounds is a perk in the Fallout: New Vegas add-on Dead Money.

Effects
You can now craft ammunition at the reloading bench using alternate materials (scrap metal and tin cans). Specifically, a single round of Guns ammunition can be made with 1 scrap metal, 5 tin cans, and the appropriate casing or hull. Most Guns ammunition types are supported:
 * .308 rounds
 * .44 magnum
 * .45-70 Gov't
 * .50 MG
 * 5mm rounds
 * 5.56mm rounds
 * 9mm rounds
 * 10mm rounds
 * 12 gauge
 * 20 gauge

Bugs

 * The Junk Rounds perk does not include recipes for .22LR rounds or 12.7mm rounds, despite containing resources for both (see behind the scenes).
 * This perk may not work at all, and sometimes crashes the game.

Behind the scenes
A new ammunition subtype, JNK, or junk rounds, was included in the Dead Money add-on, presumably for use with this perk. The new ammunition type existed for all Guns skill ammunition and provided the same effects for all calibers: 0.75x to Damage and 1.5x to Gun Condition. The new ammunition type covers two calibers which are not included in the existing version of the perk: .22LR rounds and 12.7mm rounds.

However, the recipes granted by taking the Junk Rounds perk simply produce one round of normal ammunition, rather than of the junk subtype. JNK-subtype ammunition is not used anywhere in the add-on, and cannot be obtained by normal means. If it is obtained it cannot be used in any weapons, as the ammunition is not added to the appropriate lists used to determine what ammunition types a weapon can load.