A 7 week old duck has feathers. It's easier to butcher while the duck is fully feathered. Those time periods fall somewhere between 6 1/2 weeks to 10 weeks or wait 6-10 weeks for the next fully feathered period. You can feel the pin feathers if you feel under the feathers of the breast.
It is much easier to pluck when there are no pins. Duck wax will get the pins off, but it is much easier to filter the wax if there are no pins.
A well bred and well raised Pekin should dress out at about 5 pounds when 8 weeks of age. Feather-wise, that is a good time to butcher. After 8 weeks, their growth slows and you lose the amazing feed conversion ratio of the Pekin. They do get a lot bigger, but those extra pounds cost more in feed.
At 10 weeks, an Appleyard is large enough to butcher. They will be as large as an 8 week old Pekin, and much leaner. However, I don't know dressed weight since I have yet to butcher one. They get big fast and don't use a lot of feed to get there.
A 16 week old Swedish from a hatchery will only dress out about 2 pounds and eat a lot to get there. Not worth raising for meat. My exhibition Swedish grow twice as fast and eat about a quarter of the food. I don't know how they dress out, not having butchered any of them. They are not nearly as large as the Pekin.
