Yes, it's normal. What's not normal is the gigantic breasts on the chickens you buy in the grocery store. Those commercial broilers have been carefully bred for decades now to achieve the massive amount of breast meat that they have as consumer's taste has changed and white meat has become more valued. A dual purpose bird will never have that much breast meat on them, no matter how you raise them or where you get your stock.
Be prepared, home raised chicken also has more texture than store bought chicken (even if you raise the commercial broilers yourself). Part of it is breeding, part of it is exercise (those chickens in the store probably got as much exercise in their entire short lives as your guy did the first two or three weeks), and part of it is age. The grocery store chicken is done growing at about 6-8 weeks of age, so they are still very much babies. Your barred rock has had a chance to reach adolescence/puberty at least and has had a lot longer to develop muscles through exercise and development of the sex hormones. It's kind of like the difference between veal and beef. Some people who have only eaten store bought chicken think that a 16-20 week dual purpose bird seems tough or stringy compared to what they're used to. Personally I think they're just more firm.
Be prepared, home raised chicken also has more texture than store bought chicken (even if you raise the commercial broilers yourself). Part of it is breeding, part of it is exercise (those chickens in the store probably got as much exercise in their entire short lives as your guy did the first two or three weeks), and part of it is age. The grocery store chicken is done growing at about 6-8 weeks of age, so they are still very much babies. Your barred rock has had a chance to reach adolescence/puberty at least and has had a lot longer to develop muscles through exercise and development of the sex hormones. It's kind of like the difference between veal and beef. Some people who have only eaten store bought chicken think that a 16-20 week dual purpose bird seems tough or stringy compared to what they're used to. Personally I think they're just more firm.