I'll say this again as this crops up every couple months or so...Rio 20 Gauge Buckshot is NOT 00Buck...no matter if the various businesses keep repeating bad information. Their pellet size is .29"...closer to #1 Buck.
Rio Table
Edit to add: Without buying it, I'm betting on a math error to boot. #2 buck stacks in layers of three...#1 Buck stacks in layers of two. Assuming what they say is true (.29"), the last layer would only be one pellet. It just doesn't compute. 9 #1's weigh in at 360 gr. or roughly 4/5 oz. A claimed 1330 fps. out of a just < 7/8 ounce load in a 20??? It can be done BUT.
9 #2 Bucks weigh in at 260 gr. or ~5/8 oz. In a 20 gauge hitting 1330 fps. with that load should be easily in reach.