I’m guessing you are putting in the key locks with the flat sides on the barrel to keep them from rotating.
I’d get out my Uni-bit step drill, and fine tooth round and flat files.
Drill out the center of the hole to the width of the flats, and then finish the opening with the files.
All of these tools are at your local hardware or big-box store. Probably won’t spend more than 30 bucks.
The Uni-bit is one of the handiest tools for making holes in sheet metal. You definitely be using it again.
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