First, the liability issues may cause them to say no. And with a functioning mine (and yes, a quarry IS a mine) MSHA has something to say about persons entering the property, and duties of the mine operator.
Second, rock that has been shot and mucked goes to a crusher. They have a magnet to pull "tramp iron" out of the rock, and a jaw crusher does not care what you feed it, but the cone mills that crush the finer grades may not be happy with bullets or brass that gets run thru.
What we have here is... failure- to communicate.