Too bad no 10mm auto load made exceeds the hottest 357 Mag loads from Buffalo Bore and Underwood. At its absolute best the 10mm is almost equal to the 357. To claim anything else is to show a complete lack of knowledge on the subject. You might as well regurgitate the old BS claim that it equals the 41 Magnum...
I had a Gen 3 G 20 and it ran .40 ammo with zero issues. The newer Gen 5 is the same. I don't make a habit of it, but I have never had a single problem.
There was a time when I ended up with a good bit of .40 ammo and did not have a .40. I was shooting USPSA matches, and decided to shoot the ammo through the G20.3 until I used it all up. Worked fine. Then I went back to my G21 and 1911s.
I absolutely make a habit of shooting .40 S&W through my G20 and G29 pistols! The .40 S&W works perfectly in the longer chamber because it's captured by the extractor during feeding and cannot slip out due to the limitations imposed by being in the confines of the chamber! And even if it did somehow manage to get "push-fed" into the chamber ahead of the extractor, the firing pin would not reach the primer to fire it! But let's say the firing pin developed a mind of it's own and somehow extended itself to reach the primer, which is the path of least resistance? To blow out a steel barrel and chamber rated to 180,000 psi, or to simply force the case to set back against the breech face? If you chose the first answer you're dead wrong! The .460 Rowland can chamber the .45 ACP and .45 Super safely, as the .38 Super chamber can handle the 9mm, and the .45 ACP chamber can easily handle the .45 GAP!
All modern autos capture the rim as the round feeds up from the magazine - except the 5.7x28 which uses bump feed, but is MADE to bump feed and not relevant to this discussion.
