We did this the rest of the summer. We had so much fun on Sundays that we decided to try a Saturday, too. We got to the pit early and found a skeet-shooting club taking target practice at the bottom of the pit, near the area where the trucks were loaded during the week. We watched them until noon, when they left, along with the gravel pit crew.
We went down to where they'd been shooting and saw that a lot of the clay pigeons were still intact. There were a couple of empty boxes, and I loaded all of the targets into them. We carried the boxes back up to the top of the pit, hid them behind some trees, and resumed our jumping and diving off the rim for a few more hours.
The next day we brought our pellet and BB guns and took turns throwing the targets up in the air for the others to shoot at. When we missed, they would land in the sand below, allowing us to reuse them yet again. It was as much fun as the sand jumping.