Plastic shotgun wads are a bit undersized since they are intended to be inside a cartridge in the bore. I just pick up already fired plastic wads at the range or in the field. They are somewhat stretched at the base and the petals have opened. They are free, and they fit better in the muzzleloader. At the range, you usually get a bunch that are the same since a shooter will fire 25 rounds or so and several at each presentation. They don't have to match perfectly in my experience. You can choose to cut off the base and just use the cups or you can cut and use the base without the folding portion, or use the whole thing. If you have too little shot to fill the cup, cut it off. You can prep them before a hunt or range trip and even put a little lube on them to deter the alleged "melting" and plastic streaks. With 80 grains of powder and a "square load" I get around 1 1/4 ounce shot.