Even rarer than the lauded 2nd Gen. G19 are the THREE G19 Glocks made in 9x21. Three special agents of the US Naval Investigative Service were being stationed in Italy with some work being done incognito and since they could not carry 9x19 as it's illegal for civilians in Italy these were made for them. The pistols are marked with the new caliber on the frame and barrel and have serial numbers EN260US, EN261US and EN262US.
There's an ad for Italian made holsters in one of the Glock Annuals that shows a 3rd gen G19 with 9X21 caliber markings on the slide. I think that 9X21 is a caliber that Glock makes for European countries that ban 9MM as a military round. And there's a G19 photo thread around here with a 3rd gen G19 in 9X21.
Pissing off the world since 1962