I was RSO for an officer who had an issue with a bad department reload that was improperly resized.

Which meant that the live round would not go fully into battery and would not extract. I wasn't willing to try firing the round since I had no confidence it was loaded properly.

The solution was to use a tool to disengage the extractor, then rack the slide back and use the yellow lever to enable disassembly of the pistol without firing the round. I could then use a squib rod on the removed barrel to hammer the (still unfired) round out.

For me, the lever saved the day.