Chamber Neck Dimension

[gilream]

I have a loaded round with a case neck diameter of .2492

After firing this round in my 22PPC USA chamber, the case neck measures .2511

What is my chamber's neck dimension?

 

[fdshuster]

gil: It's been my experience that you will get approx. .001" of springback, fired case neck diameter to chamber neck diameter, so I would have to say you have a .252" chamber neck. Examples for me are: 6ppc as fired at .271" with a .272" chamber. 6BR as fired .264" with a .265" chamber. 6BR .271" with a .272" chamber. 22BR as fired .251" with a .252" chamber. So, for all my chambers, including a few others, not mentioned, the .001" of springback holds true.