X2 to what FunClucks said…
I processed a 9 month old Australorp rooster (which are also dual purpose and fairly similar in size to Orpingtons)— he dressed out at 3.4 pound compared to the 6-7+ pounds I got from my New Hampshire meat birds who were 14 weeks old.
Below shows the difference in carcasses…
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…for someone who has a small family and plenty of time available to process birds, they will potentially be plenty pleased with those birds. For someone like me who is feeding 7 hungry mouths, that bird was a disappointment as far as meat — hardly worth the time and effort. I processed him because he was mean, and when I’m already processing other birds, one more doesn’t make much difference — but I wouldn’t be wanting to process multiples of him to fill the freezer, as I would need twice the amount of birds.