Economics of Violence

Economics of Violence refers to an unmarked quest in Fallout 3.

Detailed walkthrough
Pronto in Paradise Falls complains about having no good items to sell as all he gets from the other slavers is leftover junk. If the Lone Wanderer offers to help him out, he will ask them to bring him 20 Chinese Assault Rifles.

Chinese assault rifle locations

 * On super mutant masters.
 * Inside Mama Dolce's factory. The factory is full of Chinese remnant soldiers and virtually all carry this weapon. One should be able to obtain most (if not all) of them here, making the hunt very short.
 * Talon Company mercenaries often carry these weapons at higher levels or difficulty settings. Fort Bannister has frequently-respawning mercenaries with this weapon.
 * The Megaton armory houses three Chinese assault rifles.
 * Stealing individual weapons from certain characters is underhanded, but will work. Lucas Simms in Megaton carries the weapon, as well as Harkness in Rivet City.
 * Flak 'N Shrapnel's in Rivet City usually will start out with two of the rifles, and a third can be found in their room on the upper deck (Lockpick difficulty: Average).
 * There should be more than enough in the Capitol Building.
 * There is one on the shelf in the Wilks' house in Grayditch. (from the quest Those!)
 * In The Pitt add-on, three can be found on a shelf in the southwest room on the second floor of the abandoned apartments.
 * In the Point Lookout add-on, there are several in the bunker next to Calvert Mansion at the end of The Velvet Curtain quest.
 * Roy Phillips is equipped with one.
 * There is one Chinese assault rifle on a shelf by the door to the Rivet City armory.
 * There is one in the Taft Tunnel along with a full Chinese uniform.
 * There is one located in the Museum of Dave found during the tour on the wall beside a stop sign and a cattle skull.

Rewards
Pronto's shop will have a better inventory and he will also get around 400 caps instead of around 150 (see picture) to barter with. His store is turned into a "typical good gun and ammunition store," of which there already are several in the game, with an additional 20% discount.

Bugs
Once you give him 20 rifles, if you talk to him about his inventory again and agree to get rifles for him, his inventory could revert to the previous version.