My friend told me he thought it was copper head but I am thinking he was off.

any?

It might be canebreak rattler....

would this work on black limbs??

They are canebreak rattlers.

Looks like Timber Rattler to me. (Canebreak)

Yes to above, They look outstanding over black glass.

Timber/Canebrake . . Croatlis horridus.  Herpetological community and 'common names' conflict, but canebrake and timber a basically color/pattern morphs of same critter.

Canebrake on black ACS limbs.
Killdeer  

Looks great thanks killdeer!!!

Xia, as stated above they are Canebrake rattler....and yes, they look great on black limbs!!

Yep, canebrake.  Timber rattlers have similar markings but fade to black near the tail, at least in our part of the country.  

They look good on just about any bow if you like skins.