Oh I can definitely understand wanting better male to female ratios!
On average, you have a 50/50 chance of getting males or females. Averaging out of 100 eggs. Realistically not everyone will be hatching 100 eggs at a time so the results can be less statistically predictable. Sometimes you get more of one, and other times more of the other.
What kind of roosters do you have?
If you have a red roo like a rhode island red, or a gold roo like a buff Orpington, and cross him with your barred rock hens, you can tell when they hatch which gender they are. The males will have a white head spot an the females will be all black. That way you could sell the males early on to someone looking to raise males for meat.
Your odds will be the same, but you will know day of hatching who is a pullet and who isn't, and make arrangements for the males much earlier on.
There is anecdotal evidence that certain hens tend to produce one sex of chicks more often than the other. I don't know that it has been studied in a scientific manner, just that a few members here have that lucky hen who gives them more pullets than cockerels.
Whether you have a special hen like that would have to be discovered by you through trial and error. You'd be hatching chicks, noting how many were male or female, and keeping track of who is the mother hen. If your current hatches were from your birds, think about who was mom, who was dad, and what their results were (if you can). Then try other hens that you didn't hatch from, and see what happens.
