That's about like ours with the breasts. I do think that our males could have a little improvement in the breast area even though they are "dual purpose" birds. We've had some of our 4 month olds dress out at 3.5 lb. Older ones have dressed out around 5 lb. And we didn't do any fattening up, putting in a smaller pen for a while before we butchered. Might have been able to get them a little heavier if we had done that but the decision to butcher them came pretty suddenly and we just wanted it done.Around here I eat anything big enough to dress out, usually starting with the boys at about 3=4 months. Some of the bigger breeds like my Black Copper Marans and Buff Orpingtons will dress out around 2-2 1/2 pounds at that age, some a little bigger some a little smaller. The easter eggers and Welsummers are a little smaller and take a little longer to get the same size. Also they seem to grow more slowly, but both are more egg layers than meaties. Older birds make fine soup and stock.
None of mine grow out with the huge breasts you see on commercial meat chickens and if that is what you are after, you probably should raise the Cornish X. But my guys give me plenty of meat, especially on the legs and back that you won't see on that grocery store chicken.