Hi Kfelton .
That great you scored Black copper eggs from Bev s Davis with a LP line .Bev s is a best breeder in your country of a good marans. So you are lucky .
HOW TO WORK WITH A BLACK COPPER TO IMPROVE A SILVER CUCKOO LINE.
Easy for us down here and in France but not where you are. WHY?
we follow the French standard .that mean a Silver cuckoo is ER/ER based chook ( hen with hackles ) and That is NO NO in your Standard. you guy s looking for a solid Cuckoo NO hackle for the girls.
What you can do with a Black copper in your case is to create a golden cuckoo marans is easier because you will be working with a same Golden gene s+.
Here how you do t.
Mate a Black copper rooster hatched from dark egg to a silver cuckoo hen/hens = that will give you a F1 single barred cockerels ( dark cuckoo B/b+ .S/s+ carrying a Golden gene)
From here you can go 2 ways ;
Golden cuckoo = take the best F1 barred cockerel and mate him to a Black copper hen/hens ho lays dark eggs = you will get F2 50% dark cuckoo pullets and cockerels and 50% Black copper;
YEAR 2 mate you F2 Golden cuckoo between them selves = you will get F3 .double barred cockerels BB, s+s+. and a single barred pullets ( pullets are always single barred B/- ) they are your breeders and they will breed true from now on. the rest is a cull.
Silver Cuckoo;= this cross will produce a lot cull because we adding a Golden gene s+ to a Silver chook S. but could be done if you produce a lot chicks ( I m working my self with this cross and I m in the F3 generation and I tell you I hatched over 200 chicks to get 5 pure silver double barred cockerels BB,SS as F3 .a lot golden Cuckoo and silver cuckoo with a red leakage ( straw )a culls.
start a Same way like a Golden cuckoo in the 1 st stage= F1 take a best barred cockerel ( B/b+, S/s+ ).
stage 2; take a F1 cockerel and mate him to your silver cuckoo hens =you will get a F2 . 50 % of the cockerels silver cuckoo ( same with a red leakage ) and 50% Golden/Silver cuckoo cockerel a culls. Keep a best and the pure silver cuckoo cockerel. ( you can check a pullets they should lay darker eggs than they mum )
stage 2= mate a F2 cockerel you selected with a silver cuckoo hens= you will get all silver cuckoo some with a Red leakage BUT you have to watch a hackles on the girls choose only the one s are solid cuckoo and keep doing t for a few years to breed a Red gene out ( is not easy )
Hope that help. IF I was you I ll Do a Golden cuckoo you have all the best Black copper genetic to work with and you will have no Hackles problem , JUST opinion do what you like with your chooks