Arizona Scavenger

 is an unmarked quest in Fallout: New Vegas.

Quick walkthrough

 * 1) Speak with Aurelius of Phoenix at Cottonwood Cove HQ,
 * 2) Bring him NCR dogtags

Detailed walkthrough
After speaking with Aurelius of Phoenix, he offers the character a bounty on the lives of NCR soldiers. For proof, Aurelius will require NCR dogtags to be brought to him. With a Barter of 35, the cap reward can be changed to ammo and/or supplies. To inquire about the ammo and/or supplies, you will have to see Decanus Severus. To easily find NCR dogtags, it is best to head to areas with a high NCR population. These areas include Camp McCarran, Camp Forlorn Hope, Camp Golf, Hoover Dam and Mojave Outpost. Locate Aurelius of Phoenix and turn in the dogtags, you will be paid in caps for every dogtag you turn in; if you succeed at the Barter check you can trade them with Decanus Severus for ammunition, firearms, explosives, armor or food depending the amount of dogtags turned in.

These are the available trade options for Decanus Severus:
 * Armor: 15 dogtags for a leather armor, 20 dogtags for a leather armor, reinforced
 * Ammunition: each dogtag corresponds to 10 rounds of 10mm or .22 LR or .357 magnum or 20 gauge shotgun shells or energy cells.
 * Explosives: every 3 dogtags can be traded for one frag grenade or dynamite
 * Firearms: 20 dogtags for a 9mm submachinegun, 30 dogtags for a 10mm SMG, 25 dogtags for a laser pistol, 30 dogtags for a laser rifle