I used a BO/Aussie mix cock last year. I took him to a lower quality Black Orp hen, and took him a to, what should have been culled for lite eyes, Splash Orp hen. The offspring with both, produced, seemed to change about every ten eggs or so hatched. For ten eggs hatched, I was getting some outstanding quality pure blacks with the electric green sheen, only to be followed with some with alot of red leakage. Because my cock had a Meyer Hatchery from the sire, what was sold to me as a Jersey Giant, but looked like an undersized Australorp mix, he threw EE looking offspring too, in 1 outta 20 hatched, and a built in pattern gene was discovered. That really irked me too, since I had no clue what was really in that Meyer Hatchery Aussie that was the sire to my Bo/Aussie? mix. I was getting birds for a few eggs or so hatched that looked like either Black Copper Marans or Blue Copper Marans birds too. Again it seemed that about 10 egg or so in a row laid, give or take would have the same traits and then there was a genetic shuffling of the deck & suddenly these hens and this cock would produce a totally different looking bird. The cock having Buff Orp had lite eyes, the Splash Orp hen had lite eyes, and I NEVER had any Blues from them with a lite eye, WEIRD! I did show a few of his offspring, and two of them, a Blue hen and a Black cockerel at the Connorsville Show did win BV against others in that show. So you may see the same with your breeding. I would not be afraid, nor can predict accurately what you will get. But, I can say you will get the full spectrum of looks. Spaced out about every 10 eggs or so.
Since I did this breeding it opened my eyes to how genetic traits are passed down. So, I am reluctant nowadays to sell hatching eggs. I want to be the one who sees what can come out, even from my 100% purebred BO's and Black Orps lines. These traits will change on who throws what from what side of the deck of a given trait. Hope this makes sense. I had to hatch every single egg from my mix when taken to a lower quality Orp to find this out. And since this cockerel was from MAYBE the very best Buff Orp breeder in the USA, I had to see IF this boy would throw some of that breeder's line traits in these Blacks. This mixed cock acts and throws like a Black Orp.
To give an idea of what I am talking about.
Here is a Buff that I shown who has this Buff Orp breeder's line in her. She did very well at our central Indiana Poultry Show here in Lebanon IN back in Oct.
Champ English and she wasn't even 7 months old.
IS this Black cockerel, who is the same age in this pic related to that Buff pullet? I won't tell. Too many here are purists and would hate to know the truth.
I am very happy that in the APA, they judge the bird in front of them. And that is the way it should be. So please enjoy your mix & let us see down the road what you have. Should be an enlightening season for you. GOOD LUCK!