On previous occasions, we have mentioned the fact that specific screw-ups by federal officials have placed guns in the hands of some of America's most notorious mass shooters.

If not for sloppy record-keeping and boneheaded mistakes by individual officials, the shooters in incidents in Charleston, S.C., at Virginia Tech, and in Sunderland Springs, Texas, would not have been permitted to purchase guns. There could be many, many similar cases where guns were used in crimes other than mass shootings.

One could add to that body count the tragedy of Operation Fast and Furious. During the Obama era, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives knowingly encouraged gun dealers to sell thousands of guns to straw man buyers who were obviously supplying the Mexican cartels. Their hope was to track the guns back to cartel honchos and arrest them. Unfortunately, those guns disappeared after they were permitted to "walk" into Mexico. And even more unfortunately, those guns that the ATF had put into criminals' hands started turning up at violent crime scenes on both sides of the border, including at the scene of the murder of Border Patrol agent Brian Terry in 2010.

If you think the government has a lousy record on gun safety based on those data points, you ain't seen nothing yet.

Agents at every ATF office in the country are now scrambling to recover thousands of guns that an agency contractor stole over a three-year period from their National Firearms and Ammunition Destruction Branch in Martinsburg, W.Va. The guns in question were waiting to be destroyed when the contractor, Christopher Yates, stole them, according to his plea agreement. Yates sold them on, in some cases through a gun dealer in Pennsylvania. Among the takings were a number of fully automatic machine guns, which require federal permits to own.

Among the disturbing questions in this case is how this pilfering went unnoticed for so long. Yates, a security guard who had access to the entire Destruction Branch compound, was caught only after Philadelphia police recovered a gun containing a part that the Martinsburg facility had supposedly already destroyed, at least according to the records. From there, the ATF was able to figure out that Yates was to blame. But how is it that the agents at the Destruction Branch failed to notice such a massive theft operation for so long? It doesn't inspire a lot of confidence in the federal bureaucracy. Even worse, this is the ATF's only such facility. Of all the weapons confiscated or decommissioned nationwide by federal law enforcement, all of the eggs were going into this one basket, all of them overseen by the same idiots that allowed this to happen on their watch.

How many criminals were able to arm themselves through the black market with Uncle Sam's help? This incident provides a grim reminder that if lawmakers want to do something about guns ending up in the wrong hands, they should start by minding the government's own store.