Is it possible that you are not allowed to check more than what the US allows you to bring though customs?
Customs has no limit on the amount of alcoholic beverages you can import; it's just that over a certain amount you need to pay duty (although sometimes they waive that on a case by case basis). We have often brought a case per person in, with the duty precalculated for them (they appreciate that!), and all but one time have been waved through.