In sporting clays "open" competition, you may use shells with up to 1 1/8 ounces of shot. There is no minimum amount required. There is no requirement (maximum or minimum) on the amount of powder in any gauge.
For "sub-gauge" events, you have the following maximums on the amount of shot:
20 Gauge ----- 7/8 oz
28 Gauge ----- 3/4 oz
.410 Bore ----- 1/2 oz (Note: the .410 shell cannot exceed 2 1/2 inches in length when fully open.)
Lead shot sizes cannot be larger than #7 1/2 nor can they be smaller than size #9.
For "sub-gauge" events, you have the following maximums on the amount of shot:
20 Gauge ----- 7/8 oz
28 Gauge ----- 3/4 oz
.410 Bore ----- 1/2 oz (Note: the .410 shell cannot exceed 2 1/2 inches in length when fully open.)
Lead shot sizes cannot be larger than #7 1/2 nor can they be smaller than size #9.