i have several 20 rnd boxes of Winchester white box 5.56 ammo which I purchased at a bargain a few years ago when a farm store closed. It is labelled 5.56mm, product #Q3131. Is it safe for my NEF or Savage ? Unknowingly, I have run about 16 rounds through my NEF and they seemed OK.. The primers show some flattening but not an inordinate amount. No more than say, my Black Hills blue box ammo.