in addition if you cross one of those cockerels to HRIR hens then some of the cockerels from that mating will have the same genotype as the f1 cockerel. So they should look the same as the f1 you used except likely with a better type. If i understand what nic has been saying correctly.
not only better Type, most genes found on HRIR would be in homozygous state at this stage
let me make sure I understand what you are saying (since I had not considered using a single barred F1 cockerel...
you are saying to cross a Rhobebar roo overt hrir hens and then use a cockeral out of that hatch who is single barred to breed back to rir hens for yet another single barred possibility but with better type etc?
Did I understand that?
Then use that cockerel over rhodebar hens and about half of boss and all the girls would have correct barring. .. but would they breed true beyond that? Using the resulting hens and double barred cockerels?