Punnent Square Question?

You're quite right that all children of this match will be running and black. The reason for this is that each child only needs one copy of the dominant gene (an R or B) to express the dominant phenotype, and since one parent is heterozygous-dominant and the other is zygous-dominant every child will always get one dominant gene. The _difference_ is that some children will get only one copy, and thus in the future may match with a zygous-recessive organism and produce recessive children.