I've been hearing for years that this is possible for years but have been hesitant to try it, until I came across this article:
http://www.thetruthaboutguns.com/2015/06/jeremy-s/40-in-a-10mm-glock/
I could find no holes in his argument, so I went out and bought a box of .40 S&W and ran it through my Glock 20 (chambered in 10mm Auto). As expected, zero problems, and the .40 S&W ammunition is a joy to shoot out of the big G20 (10mm is also pretty tame out of the G20 if you're used to shooting quite a bit).
I plan to continue shooting .40 out of my Glock 20. It's nice being able to go to Wal-Mart and buy .40 for $14/50 rds as opposed to having to order 10mm Auto ammo online, or go to a gun shop and pay well over $20/50 rds.
Here are some comparison groups I shot from 30 feet with some PPU 10mm Auto ammunition vs. some Perfecta .40 S&W:
http://www.thetruthaboutguns.com/2015/06/jeremy-s/40-in-a-10mm-glock/
I could find no holes in his argument, so I went out and bought a box of .40 S&W and ran it through my Glock 20 (chambered in 10mm Auto). As expected, zero problems, and the .40 S&W ammunition is a joy to shoot out of the big G20 (10mm is also pretty tame out of the G20 if you're used to shooting quite a bit).
I plan to continue shooting .40 out of my Glock 20. It's nice being able to go to Wal-Mart and buy .40 for $14/50 rds as opposed to having to order 10mm Auto ammo online, or go to a gun shop and pay well over $20/50 rds.
Here are some comparison groups I shot from 30 feet with some PPU 10mm Auto ammunition vs. some Perfecta .40 S&W: