Hi farmboy. Asking questions is a great way to learn. Some folks are born knowing everything, but most of us need help figuring out new things. I remember the thread about when your heifer calved and I thought the calf was nice. You said "He is out of our limangus herd ball and my shorthorn, charolais, simmental, angus heifer. So as about crossbred as it gets"
He looked sort of dun colored, so you probably have the diluter gene from Charolaise coming thru. If so, it might be hard to get a blue calf, if that's part of why you like RB.
Anyway, with cattle that have lots of different crossed genetics, sometimes things will turn up from a few generations back on any of the parents. Like big calves from Simmi or Charolaise or Shorthorn, even if your cow is not big or the sire is supposedly calving ease.
I would get the vet to do a pelvic measurement on your cow and then you will have better information to work with. I learned this from having crossbred heifers that went back to performance growth Angus breeding about 3 generations back. They had some big calves and nothing else bred to the very same bull had big calves.