It is worth 20 gamer score, and is unlocked by firing a total of 1,000 bullets from any gun. This must be done in one playthrough.
The following weapons count towards the bullet count:
The easiest way to acquire this achievement is to use the guns the Special Forces drop upon being killed. After gathering a few of the weapons, empty each gun by firing all the bullets.
|3 Day Survivor - 5 Day Survivor - 7 Day Survivor - Bullet Point - Carjacker - Census Taker - Clothes Horse - Costume Party - Frank the Pimp - Freefall - Full Set - Gourmet - Group Photo - Hella Copter - Humanist - ∞ Mode - Item Smasher - Indoorsman - Karate Champ - Legendary Soldier - Level Max - Life Saver - Marathon Runner - Outdoorsman - Overtime Mode - Peace Keeper - Perfect Gunner - Photojournalist - Portraiture - PP Collector - Psycho Photo - Psycho Collector - Punisher - Raining Zombies - Saint - Self Defense - Sharp Dresser - Snuff Shot B - Snuff Shot J - Strike! - Stunt Driver - Stunt Rider - The Artiste - Tour Guide - Transmissionary - Unbreakable - Zombie Hunter - Zombie Killer - Zombie Genocider|
|Ammo Belt - Arthur's Boxers - Cop Hat - Hockey Mask - Infinity Mode - Laser Sword - Mall Employee Uniform - Mega Man Boots - Mega Man Tights - Overtime Mode - Prisoner Outfit - Pro Wrestling Boots - Pro Wrestling Briefs - Real Mega Buster - Special Forces Boots - Special Forces Uniform - White Hat|