Very strange bolt in an auction. Any ideas?

[cvasqu03]

Hey guys, I really dislike posting about active auctions, but I wasn't planning on buying this just to take pictures. This UZI parts lot has a very strange bolt in it. I can't say I've seen anything like it before. In fact, for a while I was thinking it may be some type of display barrel, but can't be sure.

Has anyone here ever seen a bolt like this?

https://www.gunbroker.com/item/1088461130

 

[timkel]

Ingram M10 bolt.

 

[cvasqu03]

Ingram M10 bolt.

Wow. I did not suspect that.

 

[root]

Yup Mac bolt.
At 1st I though 22lr but it appears to be a mac bolt once I saw the bolt face.

 

[cvasqu03]

It looks like someone contacted I just notice that the auction has been updated and pictures of the bolt have been removed.