Yes, the Glock 20 and 10mm are a great combo, especially with the 6 inch barrel Glock was selling for awhile. Shame the Glock came sometime after the introduction of the 10mm. Might have been more popular if the initial pistol was the Glock. (IMHO )Depends on where you are from. Some places have an abundant supply of 10mm for good prices and no 9mm at all. The .40 is a great round and the 10mm is an excellent round. With a G20, very easy to manage and such a useful range of loads out there. If your hands are small you will not like almost any but the 9mm Glocks which even then some people can't comfortably run. I personally am a huge fan of 10mm and love my G20. Hand loading 10mm will save you hugely. 10mm can take any beast in our country outside brown bears.