Most of the time the opening compound is just uneven. Many times you can reload them and they'll fire if the firing pin his a different spot.
That's what I thought as well, and did retry the rounds and occasionally the dud would fire but most often not the newer Winchester ammo will not after 2, 3 or 4 tries on different areas of the rim. When I was kid we would just re-chamber it and it would more often than not it would fire.
Not today and not with the Winchester bulk packs that I have become familiar with.

