Oops, I saw "roosters" and thought you were talking about chickens, not quail. (Not sure how I missed the phrase "going to get quail.")
Quail are also edible at any size, but some of my other details are going to be right for chickens and wrong for quail.
I have no personal experience with killing quail, but I see you already have one answer to that question from someone who does have experience
