Oh wow, great info. I hope you made a thread about it. If not it's our loss. I would love to read more about such a cross. 20 pounds in 6 months is definitely impressive. I wonder what my Red Rangers weigh. I don't even reduce their feed because I wanted to see how long I could get away with giving the unlimited feed. So far 10 months and they still lay. The one in the Dorking pen flies up an down from a 4 ft high roost too. I made a smaller roost for her and she doesn't even use it as a step to get to the high roost.
Unfurtunatlt I did not have the foresight to make a thread about it

I only started feeding free choice at about 4 months, he grew more like a ranger up until that point. I think if he’d been given free choice to start with he probably would’ve been about 8lbs by 12 weeks or sooner. He dwarfs even his dad who’ve I’ve weighed at 15lbs

He’s not currently as heavy as he was, I had to implement a new feeding regiment for him as I want to use him for a project. I’d say he’s around 15lbs at the moment. He’s my only one as I’ve had some trouble with his mom being a little big for even my ranger and so I get about 50% clear eggs and the others just don’t seem to be too thrifty when hatching.

I had three make it to lockdown, externally pip and then quit on me

The most interesting thing to me is I believe my hen throws sex links. The first time I hatched from her I got a black and a white chick. The black one died and the white one turned into Hulk, as I’ve named him

The second time I put her under my Australorp rooster instead of my ranger and though none of those hatched when I cracked open the pipped eggs there were two colors, black and white. I don’t know if that’s true for any other hens but it was an interesting observation I think.
My red ranger hens will be 2 in March and are some of my better layers, 5 eggs a week on average. The biggest is about 10lbs and the other two are around 8. I’ve never withheld food from them and they’re just as active as everyone else. Yeah, they seem to be able to get up with everyone else just fine! I’ve had mine fly 4’ Fences before. Mine started laying last November and didn’t quit till this fall when they went into molt. I know at least one is laying again.
This is Hulk, he’s 8 months in these.
He makes normal sized hens look like bantams!