I wondered if this could happen as the rounds are virtually the same except in length. Has anyone else done this before? Kind of like shooting 38 special through a 357 mag, well sort of. I still would not do it though.
Not a good idea, because the .40 cartridge will be held by the extractor ( not seated in the chamber ) . The extractor could break. I have a .40 cal barrel for my 1911 in 10 mm. The 40 cartridges feed from the 10 mm magazine with no problem. Lone wolf makes a drop in 40 cal barrel for the Glock 10 mm. You might need a 40 magazine for the Glock .
Married 28 years---I'm starting to think it might work out.
Second Generation N R A Life Member