You'd be surprised how big of food a snake can eat. General rule is 10% of body weight or thick as the thickest part of the snake. With that said, I have all of my guys stuff that has made them look like they ate a football afterwards and I almost have to roll them into their warm hidesBut a couple days later and they are out and cruising. My advice though is if you feed an extra large meal one time, the next time you feed a smaller than normal meal. This adds variation. I do this to my gals all the time and I even try and vary up the food items. Give em a rat one feeding and then a mouse the next. This really only works on my small BCI as I haven't found anywhere local to get quails for my big BCI girl. I think I found a guy local for rabbits but i'll have to check to see how small of rabbit I need to get to compare to a large rat. Anyways, if it was me, I would try and get your BP switched over to rats asap as it seems some BPs will imprint on a certain pretty item and you don't want that to be mice especially when he gets to 3-4' and needs like 6 mice per feeding.