That could be your problem right there. They're muscle bound and from what I understand, a lot of cornish breeders use the AI system for reproduction.
Well, heck, I hadn't read that anywhere but it makes sense. He's not "massive" per se, all of my cornish look medium sized, but when you pick them up they have quite a bit of heft to them. Part of what makes them look so small is the tight feathering. If they were poofy feathered, they'd look gigantic.
Well that makes me feel a bit better - but he was supposed to be part of my meat bird project, obviously that didn't go so well. I have a couple cornish hens but have had no luck at all breeding them. One has been broody since February. Another only squats for the turkey tom. The last two fly out of the enclosure at first light and spend the day in the woods foraging. None of them are fertile. Guess I've got to figure out what I'm going to purchase in December to reset my meat bird program.