In the early 2000s (specifically 2006/2007, I believe) US Delta Force decided to replace its .45 ACP 1911 pistols with something having a larger magazine capacity. After testing a number of different platform initially, they settled on two to purchase and fully evaluate. These were the STI 2011 (a double-stack 1911 platform) and the Glock 22, both in .40 S&W caliber.

The unit ended up keeping the Glocks and returning the STI pistols to their manufacturer as unsatisfactory, largely because of magazine reliability issues. The STI 2011 of that period was designed around a .45ACP cartridge length, and the magazines were significantly longer front to back than needed for standard .40 S&W ammunition. This was not a problems for competition shooters, who could load their cartridges to a long OAL to properly fit the magazines, but Delta did not have this option, since they needed ammunition that would also fit the Glocks.

As you might expect, there is a lot less PR value in having your pistols rejected by Delta than in having them purchased by Delta. When the guns were returned to STI, they were subsequently sold off as simply used .40 caliber 2011s, without mention of their Delta provenance. Some people who knew what they were snapped them up, but some went to people who may still not recognize the provenance of what they have...