I tried my hand at making shot loads with cut off .308 cases years ago. I sharpened the edge of case and cut small overshot and over powder wads from the cardboard off the back of an old tablet and seated them with a pencil. I put a drop or two of Elmer's glue on top to seal things up nicely. I don't recall how much #9 shot I used or what powder combination. They shot good patterns but wouldn't work the action. I had to manually work the action after each shot. The new shot cartridges on the market will work the slide just like a regular slug and work quite well. They are a bit pricey, but I don't shoot that many of them, just when I find a copperhead around camp. Loooks like a .00 buck wouldn't seal things up as I believe it's only .32 cal....unless you put one heck of a crimp on it.