Tangentially related, the military has been “losing” ammunition and weapons for a shockingly long time, and in the 80s Fort Bragg (the largest military base) was remarkably easy to rob.

In 1986, investigators for the United States Congress and Department of Defense reported growing concern in the U.S. Armed Forces over missing weapons. Hundreds of millions of dollars in military arms, ammunition, and explosives had disappeared.

A congressional report on Fort Bragg cited a large amount of missing ordnance recovered around the post, including 148 pounds of plastic explosives, 142 pounds of TNT, 1,080 feet of detonating cord, 13 hand grenades, and 35 antipersonnel land mines. Some of the weapons and explosives turned up in private homes.

From Bring the War Home: The White Power Movement and Paramilitary America.

And that was just at Fort Bragg, in the 80s when post-Vietnam violent white supremacy was taking shape.

The Branch Davidians also had a 50 caliber in 1995. No one is sure how they acquired it.

I have to imagine desperate soldiers might take to selling it instead.