What AK103K said.
It would be sort of stupid and poor judgement to use NATO brass in WWB stuff but Winchester is going through some trying times moving down south and closing the East Alton plant.
Either a disgruntled union worker who is fixing to lose his job dumped the wrong brass in the feed hopper or a non union newbie southern worker dumped the wrong brass in the feed hopper.
Either way the stuff should have been caught, culled, and destroyed.
Since WWb is 115 grain and NATO ball is 124 grain, it opens a whole can of worms as far as liability goes.
I would either
A. tell Wallyworld what you found, likely to not do much good since they will just dump any boo-boo's on the manufacturer anyway.
or,
B. buy a box, call Winchester and report what you have found.
They will issue a call tag, send a rep to the store, pull the ammo if it is mixed, and issue a recall notice.
You will be sent a paid return tag and they will send you a new box of ammo.
No explanation, thank you, or anything like that.
You will just get a new box of ammo in say, four to six weeks 'cause that's how they roll at Winchester Ammunition,,,,