Back in the 1960's, I used to load a Federal Paper hull with a standard scoop of Red Dot from a Lee Loader (about 18.5 grains), a nitro over powder card wad and fill out the hull to about 1/2" of the hull mouth with felt wads. The Lee crimper would put a nice roll crimp on the catridge and it gave a louder report than a standard trap load. Nice flames at night too!
If your careful you will be able to pick a couple out of almost every box of shells you buy ... seriously there are a few in every box of shells out there ... I swear there is ... trust me there really is a couple of blank shells in every box ... that is the only excuse and reason why I ever miss a bird is because I was shooting a blank.