Are you talking about the long clamps used for covers on an oddball panel Sq D made years ago? With sharp pointed clamps that go nearly all the way to the sides of the panel can? One of the few truly stupid things Sq D ever did was make that panel. I can't remember the model or common name for it. I only saw one of them. Also had a weird breaker with some kind of flexible strips to terminate. Someone designed all that on a Monday following a 2 week drunk or drug binge.
That was the old style NEHB panel, commonly used on 480/277 Volt systems.
On another note, those Square D panel cover screws have unique threads that make the screws tighten twice as fast. While they may
appear to be machine screws, they are not standard machine screws. Square D recently has included a couple of extras in each panel cover in case you drop/lose one. I now have plenty of extras on hand in the truck, and will use them when encountering a box that is missing one of more cover screws.
But there have been times where a panel cover screw was missing, and the inspector is coming for the final. I have used machine screws,
green screws, tek screws, and yes, even sheet metal screws to secure a panel cover. I've even used those Square D cover screws on a different brand of panel in a pinch
[GASP!].
Inspector didn't seem to mind so long as the cover was securely fastened!