I've had "jumbo" coturnix since April. They were the largest I could find locally, but I know they are not as large as some of the jumbos out there. My adult stock ranges from 6 1/2 ounces to just over 10 for my biggest hen. Yeah, not that big. My egg sizes were ranging from 9-13g with an occasional 14g. My first batch of chicks I set from my biggest eggs, 13-14g. My young birds are bigger, not sure exactly how much since I don't take the time to catch and weigh them. I do weigh eggs however, and now that my young birds have settled into laying regularly I took the time to average the egg weights. My original stock has averaged 11.8g eggs last week. My home-bred birds averaged 13.3g eggs last week. So in just one generation I increased the size of my coturnix eggs by a gram and a half! This week I'll be setting some of these bigger eggs, 14-15 grams, and see what increases I get in both egg size and bird size.