I have a book on the 1911 that shows two blown 40 cases fired from a 10mm 1911.
The case gets ahead of the extractor, and the long firing pin on a 1911 is able to reach it.
That didn’t sound quite right. So I had to go check for myself.
Using a Colt Delta Elite, I see the firing pin could indeed contact the primer of a .40 that was out in front of the extractor and seated at the end of the chamber. However, being seated more deeply in the chamber, the case would be fully supported at the moment of firing. Much more so than any 10mm or .40 that was chambered with the case head up against the breech face. This is actually an example of a
fully supported case. See below.
For comparison, here is what a 10mm looks like when chambered correctly. Notice the unsupported area in front of the extractor groove. This is normal.
Now what would happen if one fired the deep-seated .40, without the mass of the slide directly behind it, the case would be shoved backward, snapping the rim past the extractor until it comes in contact with the slide, and then continue cycling as normal. So true, the case would begin to move out of the chamber while the pressure was higher, but it would still be stopped at the point where the recoil cycle usually starts, and with the same amount of uspported case at this point.
I suspect the instance you read about was caused by a gun with an excessive unsupported area of the chamber. I understand 10mm brass is thicker in this area, and so the issue never manifested. When a thinner .40 case was fired in this particular chamber (with the rim either in front of or behind the extractor), the case was insufficient for the excessive chamber and it failed.
It’s a thought, anyway.
FWIW, I’ve fired a couple hundred .40s through a Colt 1911 without issue, and through a couple of Glock 10mms as well. The only “issue” I have noted was that having the case head not pressed firmly against the breech face allows for excessive primer flow. Reading the primer gives the impression of a massively overpressure cartridge. However, it is just from having insufficient support for the primer.
Having said all of that, I have guns chambered in both calibers, so I can shoot the “correct” cartridge in each gun. But should I find myself with only a 10mm and no ammo was available, I would not be uncomfortable substituting .40 for use.