What color of B/S chicks,and do you have pics? Some can sex peachicks at hatch,others are sexlinked,and black shouldered chicks that will eventually become males exhibit darker feathers across the backs and the cuticle in the covert wing feathers starts turning black at about 2-3 weeks of age.B/S hen peachicks will slowly change their flight feather color from yellow to lite brown-tan but their backs will basically stay yellow slowly changing over a few months of time.
A picture taken across the top of it's back would have been best.That aside you can already see the cuticle of the flight and covert wing feathers are developing with black pigment.You can also see this color expanding outward on these flight feathers as they grow out. Hen b/s keeps the rusty-lite tan color for their flight feathers as adults,so the key is looking at the next group of wing feathers where if a male,these feathers will eventually become black in certain colors.Keep in mind black shoulder is a pattern,,not necessarily the color.Opal and Silver black shoulders are 2 examples of this pattern that do not have black wing feathers when mature.Your above pic especially of the back of the chick has a lot of sunlite on it making the chick look white or lite yellow on it's back which would indicate it's a hen if indeed the back of the bird is basically mostly still yellow..That being said the wing is much more visable in your pic,and with all the color it's showing especially in the covert wing feathers,with black midribs-cuticles already present this strongly indicates it's a male.A picture taken across the back of the chick is needed.