There are .22 conversion kits available for Glocks. Go out and buy yourself a Ruger SR22. You would never think twice about making your Glock fire a smaller caliber round. And they are very affordable!
A friend of mine has what he calls a "Chinese Assault rifle". It fires 7.62. I have fired it a couple of times and it is quite the monster! Fun too! Of course the Chinese copy everything! Wouldn't be surprised some day to see a Chinese Glock. For all I know, they probably have it already!