I have two White Cornish Rocks. I have been raising birds for years and I've always been good at telling gender almost 100% accurate but I've never own such fast growing meat birds before. They have slight crowns and they are bright red. I'm pretty sure they are pullets but not sure enough, I need to know for a show. Does any one have any suggestions how to tell 100% with these birds? Oh and if it helps they are a little over 4 monthes old.