What is it?

[ArtS]

If there is a friction fit in picture #1, I am going to guess a chamber measuring tool. Insert the inner piece into the base until barely held, insert into chamber, close gun and reopen, then measure OAL. Looks like the inner piece is non-tapered and would indicate the length of a fired case.

[ArtS]

Originally Posted by Arthur Shaffer

If there is a friction fit in picture #1, I am going to guess a chamber measuring tool. Insert the inner piece into the base until barely held, insert into chamber, close gun and reopen, then measure OAL. Looks like the inner piece is non-tapered and would indicate the length of a fired case.

Sorry. I took the opening description to mean that the head part would fit a 12 ga chamber.

Sooo...

What is the the diameter of the rim and head section? My same guess would cover a 10 ga or 8 ga chamber length gauge.