Yep your roo is Heterozygous barred with only one copy of barring which makes him darker barred like Barred Rock hens. So he is probably mixed but yeah if bred with a non barred hen like a RIR, half of the chicks will be barred and half will be non barred with no correlation to the sex. If he is bred to a barred hen, all of the males will be barred,half of the females will be barred,and half will be non barred.