A particular lot of Winchester M855 ammunition is being recalled by the manufacturer:
From Winchester’s site:
“Olin Corporation, through its Winchester Division, is recalling one (1) lot of its 5.56mm M855 62 Grain PENE centerfire rifle ammunition.
You can read the full recall details here.
I know sending ammunition back to the manufacturer isn’t something anyone wants to do in this environment, but don’t risk it folks. It’s just not worth it.