The poults produced from a Blue Slate tom and a Bourbon Red hen (if they are pure and not hiding any recessive color genes) will be 50% Rusty Slates and 50% Rusty Blacks.
Rusty Black
http://www.porterturkeys.com/MRustyBlack.jpg
Rusty Slate
http://www.porterturkeys.com/MRustySlate.jpg