BCM bred to black would yield very overmelanized BCM offspring and would take a while to breed the black back out. If you use a nicely coppered BCM cock bred to black hens you would have to keep breeding the female offspring (daughters, granddaughters, and so on) back to the original sire BCM cock to breed out the black. You would have to keep doing that until they were no longer overmelanized.
if you breed a true Black marans E/E S/S MI/MI ( I don t think does exist ) to a black copper marans you will never get a black copper again ,because the E genetic family is dominant to the ER .
to know if the black chooks are true black or a black copper they should be crossed to a Leghorn ( Dominant white ) if the progeny is pure white than the Black chooks where a true black . but if the progeny is white copper ( white with some gold on the hackle and saddle ) than the black chooks where bad black copper .
that how I find out mt black are not black and my splash are not splash but dominant white .
the French never fancy to breed the pure black because they knew it is not easy to keep the black copper strain pure if the black one are around .
I only saw one true black marans rooster in Italy 3 years ago , very rare and precious .a lot planning around him to take him to France ( like France is full of a good breeders !!!!!!!!!!!!1) they couldn t bred it them selves . what a joke .
I m sure your pullet is a black copper 100% mated to well colored rooster will yield a high proportion of well colored progeny .
The Black we are trying to avoid is the one with a black beak ( rooster) , black comb ( both ) .black wattle( both) , black shanks ( rooster ) , black eyes ( rooster ) .
I found a black hen if they have orange eyes and well red comb and wattles mated a correct rooster they give cockerel with a rich red copper because of the extra mahogany and melanin .
chooks man