I agree with what you're saying! They are extremely large! Though their loose feathering just adds to it, lol. My boy is just over 28 weeks, stands head high above my knee (I'm 5' 8"), no idea on weight, but picking him up is definitely an all hands on deck kind of situation, lol.Two other considerations are Floof and meat.
Orpingtons were bred for a nice full meaty breast. How much is actually fat I don't know how to tell.
I've never had an American Orpington, but this year we got English Orpingtons... and wow. The roo we chose to keep, Clifford, is massive. Some of his appearance is floof, it compresses under hand like a feather pillow.
It had been a while and some growing since I'd picked him up when we had a hurricane coming and were moving birds inside. Most can tuck up under one arm easily. I went to pick up Clifford and dropped him. He was so heavy and the floof made it hard to settle my hands in the right spots, poor boy. Grabbed him again and found I had to hold him away from my body in front of me because my arm wasn't enough to wrap around him. I really need to weigh him (somehow?).
I know he's not getting excess fat in his diet and everything yummy he gives to his girls. So, I'm guessing all his pounds are meat?