Merry Christmas, Paul~
I will be posting a true step-by-step for Mallards within the next week or so.
For the Drake Mallard chests, you could go with straight Behr Oxblood. However, I usually underpaint the chests with the same dark brown color I use on Black Ducks and parts of Mallards: Espresso Beans. Once the chest paint is dry, I stipple over it with the reddish Oxblood.
All the best,
SJS