Help identifying unknown parts bushings ???

I recently bought a lot of mec powder bushings, these were in the lot they defiantly are not mec powder bushings. I have looked around at Hornady RCBS and other companies and I cant figure out what they are. I was thinking powder through bushings or some kind of neck sizer like an m die. Honestly I don't know just reaching out to see if someone can help identify them.

Attachment 323519

Can you post a side view? Hard to tell from the top view.

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Attachment 323522

had to do some image resizing to get it to post

Looks like Ponsness Warren window bullet seater inserts to me. If so, the groove has a c-clip that holds a small ball bearing. The ball bearing protrudes into the cylinder just enough to keep the bullet from falling thru.