This year for some odd reason I have seen more post about meat birds not growing, most of them finaly figured they didn't get Cornish X's from the hatchery. IDK what the deal is but there have been a few hatcheries that have been shipping the wrong birds or a substandard variety of meat birds. As you mentioned there is realy no doubt when you see a true meat bird grow, they just take off and gain very well very fast. Perhaps they messed up your order, and since you have had them before and know how to care and feed them out, that is a none issue. Call the Idiots at the hatchery and see if by chance they will admit their mistake and send you the right birds. I wish you good luck.