Help identifying unknown parts bushings ???

[Scooby]

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.

323519

[MarkP]

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

[Scooby]

323521

323522

had to do some image resizing to get it to post

[Devon]

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.