Gunsmithing How to measure freebore

[Dunraven]

I offered to list a friends' rifle for him. He cannot track down the original gunsmith, and does not know things like freebore. It seems that invariably someone will ask for this dimension. Is there a way a non gunsmith can measure this?

 

[mudpig]

Taking a chamber cast with Cerrosafe or sulfer and measure what you get.

 

[Mordamer]

It might help buyers if he knew the seating depth of a popular bullet to touch the lands. For example, "105 Hybrid is touching the lands with an overall cartridge length of 2.800".