I was chugging along doing some .45 acp cases when I came to one, then two, that I could not run the decapping pin thru. Both Winchester. Both apparently once fired, judging from the primer residue. Both had noticeably tapered firing pin holes. On the primer side they are fine, but on the opposite side they are so small the pin will not pass thru. When you make enough of something you will mess one up once in a while, but in over 50 years of reloading I have never seen this before.

The primer indentation is probably from a striker-fired design, ala GLock.
The interior problem you describe sounds weird. Perhaps the punch or bit that's used in manufacturing the brass had broken, or worn-down at end of it's service-life?

So you are saying that the hole from the primer to the powder is tapered?
That would be a first and a pretty radical taper.
Is it a clean hole or does it have burrs? That would back up the previous post.

Like we've said before:

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