like you I just got once fired Winchester 7-08 brass, so all the brass I have is the same headstamp, instead of sizing 308's for 7-08 and trying to keep up with.

while I convert 5.56/223 brass to 6 mongoose, the shoulder angle is different, and once it is fired, it wont chamber in a 223/5.56 anymore as the taper is different on the case.