Eightbore is using legal maximum loads. Skeet rules of the NSSA allow a maximum of 232 grains of shot in the .410. That is a gain of about 6% in the weigh of shot over the 218.8 gr. of a true 1/2 oz. The advantages of using magnum shot in the .410 are better patterns due to a decrease in the number of mutilated shot, and an increase in the number of shot because magnum shot is lighter than chilled shot. When shooting the .410 every shot counts, literally.