I don,t understand the" luck factor" in breeding,never have and hopefully never will,luck plays and played no part in any working dog breeding,its a get out clause for a lack of belief in what you have bred,IMO. agree to a certain point Morton , you must've bred a lot of 100 % litters then if no luck was involved and it's all down to breeding ? Edited to add we are talking earth dogs here not bushing dogs ain't we ?