When the .40 first came out, back around 1990? or thereabouts, I was already shooting a Colt Delta Elite 10mm, and working in a gunshop/shooting range. We got in a case of .40 ammo (Winchester 20round boxes) and as a lark, and out of curiosity, I bought a box and tried them out in my Colt. I had zero issues, they fed, chambered, shot, extracted and ejected just like Winchester's Ranger 10mm loads. Exactly like them.
Curiosity satisfied, I went back to my 10mm ammo, as I had (and still have) a lot of Midway-headstamped Starline brass. I haven't tried that in my current RIA 6" 10mm, but I suspect the outcome would be exactly the same.
I would not do that in 1911. If you damage extractor you will probably not be able to just drop in spare one while in the field. Not sure about Colt 1911, but I had to use jewelry files and fine grit sand paper to replace extractor in Armscor 1911 pistol. It would not fit in even though it was factory Armscor part for .45ACP gun. You can easily drop in new extractor into modern clunker like a Glock.
