Large Breed vs. regular Puppy food

Question
We were feeding our 6 month Lab Blue Buffalo Large Breed puppy food since he was about 4 months old.  Recently, due to running out of food, we feed him the Regular Blue Buffalo puppy food and his stool seems to be a lot firmer.  Is there any issue with feeding him the regular Puppy food.  FYI- we are planning on taking him off his puppy food at around 9 months.  

Thanks,
Pete

Answer
I am not sure what all the differences are besides the large breed being less calorie dense.  Maybe it would be just as well to make the switch to adult chow now if the large breed chow is a problem with the stools.  The regular will promote faster growth than may be best for his developing joints.