I like raising meat birds. I have raised both cornish and rangers myself. Here is my recipe for raising meaties.
With the CX I took away the feed at night. Only with the CX no need for the RR. Medicated feed I only used for the first few weeks. Then its un-medicated 20-24 % protein feed. For the final 2 weeks I feed all flock pellets with cracked corn and oat meal. I find it gives them just a little more fat and a wonderful flavor. Plus they get to eat well before the big day.
I found both breeds got around well. Yes the CX took more breaks. Never went over 12 weeks with the CX. They dress out 9 or 10 lbs. RR I waited 12 to 14 weeks. I Like the RR best. The breast are smaller than the CX but they have large thighs and the flavor throughout it awesome.
if using a kill cone while dispatching keep a hand on the bird. They can easily flop out, More likely if they are large. I now wrap them in a towel putting the head in a bucket. Doing the chickens never really bothered me. The pekins are another story. For some reason ducks take forever to die