January 17, 2024: The US military spends about $10 billion on small-arms ammunition annually. The most common caliber ammunition used by the US military is the 5.56x45mm NATO Standard round. On average, an American soldier carries around 210 rounds of ammunition for their primary weapon, which is usually an M-16 or M-4 automatic rifle. U.S. military depots store an estimated 15 billion rounds of small-arms ammunition. The Blue Grass Army Depot in Kentucky is the largest US military ammunition storage facility.

Small arms ammunition typically remains in storage for up to 20 years. The US military uses a variety of small-arms ammunition in combat, including 5.56mm, 7.62mm, and .50 caliber rounds. The US military replenishes its ammunition stockpiles on a regular basis, based on usage and demand. New military ammunition undergoes extensive testing and evaluation to ensure reliability, accuracy, and performance.

The US military transports ammunition by air, sea, and ground with the same degree of security large shipments of civilian rifle, shotgun and pistol ammunition receives. Ammunition storage facilities are heavily guarded and protected to prevent theft, sabotage, or accidents. The United States has its own ammunition manufacturing facilities but also contracts with private companies to increase production.

Obsolete or surplus US military ammunition is usually disposed of through a demilitarization process that includes controlled detonations or other specialized methods to ensure safety.

Twenty years ago, the United States purchased over a billion rounds of 5.56mm ammo from Taiwan at the onset of the invasion of Iraq while American production facilities were upgraded to handle increased wartime production. Before September 11, 2001, the U.S. Department of Defense bought 350 million rounds of 5.56mm, 7.62mm and 12.7mm of ammo a year. Most of this was 5.56mm, for M-16s, M-4s and light machine-guns. By 2004, that was up to 1.2 billion rounds. This increased to 1.5 billion rounds in 2005 and later to over two billion rounds a year.

The U.S. Army has one very large ammo factory at the Alliant Lake City plant in Independence, Missouri. For a long time, this plant produced about 1.2 billion rounds a year. After, although that has since been expanded to 1.5 billion pounds a year.

Additional ammo has been obtained by, first, drawing down war reserve stocks. Taking over half a billion rounds from those stocks, plus buying even more from civilian manufacturers in the United States, Canada, Taiwan, and Israel, working round the clock, and putting mothballed production facilities to work, kept the troops supplied. The current high production levels will remain until the war reserve stocks are rebuilt. In the meantime, training will continue to use more ammo than in the past. In the 1990s, use of live ammo in training had been allowed to decline. That stopped after 2001. Ammo usage in training will remain at high levels, though American troops have left Afghanistan and Iraq, at least until the lessons learned this time around are forgotten.