...and function fine in a Kahr PM45. Ya learn something new every day!

Some might need a little taken off the top of the latching notch in the magazine body.
I had one that fit and functioned, and 6 or 7 others, that did work, but they were tight to get to lock in. I wouldn't try to run those without modifying them to fit.

I don't know if that would make them unusable in a 1911 or not. If it did, you would have to make them easily identifiable. Maybe a small magazine sleeve down against the base plate that would keep it from being inserted all the way in a 1911.