It is really hard to tell from pictures but he appears single barred to me. A double barred bird is just as the name implies. The lighter color barring will be wider then the darker color, that is what makes the bird appear lighter in color. If you look closely at your bird, in real life, notice the width of the bars. You should be able to tell if the light bar are wider then the darker bars or if the light bars and dark bars are close in width (single bar). Not all supposed "pure" RB will be double barred. I think it will be up to us to work at improving the line and really get closer to the true "pure" breed.
 
Just a note, I am far from an expert and really just a babe in the world of chickens so hopefully some of the more experienced posters and genetic gurus can weigh in on this.
 
Penny