5/8 ounce of number 9's is 355 pellets. 5/8 ounce of 7 1/2 is 211 pellets. That is a difference of 40% less in pellets. A half ounce in the .410 is 284 and 169. I would rather use 7 1/2, limit shot size to reduce crippling and wounded birds by what we would call over spray or fringe pattern. It becomes a trade off in the end. How many 7 1/2's vs. 9's are needed to bring down the average quail? Extra pellet numbers against energy. And I feel that quail are one of the least hardy birds, easiest to bring down with fewest hits. Sometimes hard to find and hit but when hit they go down and stay down. Not like pheasant which will run a marathon if wounded or a smart Black duck which will dive and hide.