(
Just FYI...site being very weird...I am not typing in bold or yelling in large font....just how it is coming up. Sorry)
Don~ I am probably wrong when I use the term 10%, but at one time it was written not to exceed 10%, granted it was before the accepted standard was in place. I will no longer use that term, but will post the current standard for the Black Copper where it states information about the copper in the breast.
From the MCCUSA Site:
Black Copper Standard of Perfection
Male
Comb, Face, Wattles, & Ear-Lobes: Bright red.
Beak: Horn, black shading permitted.
Eyes: Reddish bay.
Head: Lustrous deep copper, neither yellow nor mahogany.
Neck— Hackle : Lustrous deep copper, neither yellow nor mahogany. Some feathers, especially in the lower hackle, may include a narrow dark stripe through the middle of each feather, terminating in a point near its lower extremity.
Front of neck : Black with markings of deep copper.
Back: Lustrous deep copper.
Saddle : Same as hackle.
Tail— Main Tail :Black with slight luster.
Sickles and Coverts : Lustrous black.
Wings—Shoulders : Black.
Fronts : Black.
Bows : Deep russet red.
Coverts : Lustrous black.
Primaries : Black.
Secondaries : Black, exposed portion forming black wing bay.
Breast: Solid black or with a few copper spots. Not laced.
Body & Stern: Black.
Legs & Toes— Lower Thighs : Black.
Shanks and Toes : Shanks and toes light to mid-slate, showing pink between the scales. Bottoms of feet pinkish white.
Shank and Toe Feathers : Black.
Female
Comb, Face, Wattles, & Ear-Lobes: Bright red.
Beak: Dark horn.
Eyes: Reddish bay.
Head: Lustrous copper.
Neck - Hackle : Copper, with a narrow dark stripe through the middle of each feather, terminating to a point near its lower extremity.
Front of Neck : Black with markings of copper.
Back: Black.
Tail: Black.
Wings: Black.
Breast: Solid black.
Body & Stern: Black.
Legs & Toes—Lower Thighs : Black.
Shanks and Toes

ark slate, bottoms of feet pinkish white.
Shank and Toe Feathers : Black