Here's a suggestion....for better feed conversion and a finer texture on the meat, you might want to try Plymouth White Rocks instead of the BOs. I've had them both and the WRs beat the BOs hands down on all things to do with food production and they are hardier stock, no matter from whence they are sourced. They are better foragers, fatten well on pasture, are gentle and calm birds both male and female, and feed thrifty.
Another suggestion...since you usually eat them in soups, why not can them each year instead of freezing? It's a better option for producing a juicier, ready to eat product and doesn't depend on the power being on to keep them preserved.
Suggestion three....if you want them to forage more and not depend on bagged feeds so much, start them out on pasture by 2-3 wks old, preferably with a broody mama, and they will learn to look there first for their tucker. If you start them out penned to bagged feeds when they are young, they will always look there first for food and won't forage quite so well.