East German 9mm Makarov pistol chamber gauge. What does it measure?

[firstchoice]

Found this listing on Ebay.

https://www.ebay.com/itm/373833781828?ssPageName=STRK%3AMEBIDX%3AIT&fromMakeTrack=true

What does this gauge actually tell you about your Makarov? Does it determine throat wear or is it for the chamber? How is it used? Just curious. I have a good selection of Makarov's and was interested in checking the barrels.


firstchoice

[Greasemonkey]

My best guess, it's head space gauge or for measuring a chamber after a barrel replacement and for use after sizing.