In this picture, the barred-rocks from front to back are hen, roo, hen. They were about 8 weeks old. Notice the difference in coloring. The roos are much lighter than the hens.
This is my PBR. I worried he was a hen till he started crowing constantly about 4 months of age. Now I need two hens for him
Here is a link from another BYC member with awesome pics of his barrs (hens and roos). Maybe it will help you. It helped me figure it out too. So many hens have large combs but I do think Barrs do.