Couple of months ago, I acquired a bag of range pickup brass. I knew that overwhelming majority of it was .45 ACP. Today I dropped that bag of brass into the tumbler to clean it before sorting it. Bad idea. It seems that when you're tumbling brass, a piece of .40SW will wedge itself into a piece of .45 ACP during the tumbling process to the point where it takes pliers to extract it. 9mm brass is bad enough, but .40 SW brass seems to like to try to hide in .45 ACP, like it's ashamed to be seen in company with the larger brass.
Aggravating is what it is. That'll teach me to take a shortcut sorting brass.