Bone-in fried chicken pieces not cooking through

Props for butchering your own chickens; this is an important kitchen technique, and yields lots of nice scraps for stock. It can also save a good chunk of money at the grocery store. You should be able to get cooked-through meat and perfectly cooked crust through frying alone, for both white and dark meat. This is a matter of chicken size, oil temperature, and cooking time.

Your trouble cooking the meat through suggests that you are using a chicken that is too large. A frying chicken should be between 2.5 to 4.5 pounds [1-2kg]. A larger bird, like a 5 to 7 pound [2.2-3kg] roaster, will take much longer to cook through, and is not generally appropriate for frying. If you are stuck with a larger chicken, save it for another cooking method.

Once you get the right bird, a thermometer plays two import roles in this process. First, it lets you check the temperature of the oil. Since the oil cools when you add food, you may need to adjust the flame to maintain the desired temperature. Second, a thermometer is the best way to gauge doneness of chicken: dark meat should read 165°F [75?] at the thickest part.

This recipe from Bon Appetit instructs you to heat the oil to 350°F [180?] and, after adding the chicken, maintain it at 300–325°F [150-160?]. At this temperature range, they are getting good results in about 12 minutes. Hopefully this time and temperature work for you.

If not, you can resort to baking at 350°F [180?] until the chicken comes to temp; 10 minutes tops. Make sure to put the chicken on a wire rack inside a baking sheet: this stops oil from pooling under the chicken and makes sure it stays crisp on all sides.

These instructions take a further step for maximal crispiness: they fry for 10 minutes at 300°F [150?], bake for 5-10 minutes, cool in the refrigerator for at least 1 hour, and re-fry at 400°F [200?] for 5 minutes. This is a lot of steps, but if it solves your problem it might be worth it!

The best/worst thing about cooking is there are a thousand ways to do every task. Another option is to blanche the chicken first in oil, as you would do for potatoes. In other words: batter your chicken pieces, fry them in lower temperature oil (I do it at roughly 145 Celcius) until fully cooked. Each cut will be cooked at a different time, so use a thermometer to check each piece until you've done it enough that it is part of your repertoire. At this point you can toss them in the fridge until tomorrow if you want to speed up tomorrow's evening meal. Then at service time you crank your oil up to 190 Celcius, drop your chicken and cook until heated thru and crispy, and toss with sauce if desired. I have been using this method for 3 decades in Japan and Canada and both my customers and my family regularly give positive feedback.

Regarding brining: I do a 2 day brine with big things like 3 kg Turkey Breasts. But with a chicken IMO 2 days is going to result in a lower quality texture. Try brining for less time, and if the meat isn't seasoned enough then make your next brine stronger.