Thread: Post firing case head expansion - what to expect?

Hi all
Just doing some load development for my 284 and been miking the case heads at the web. Getting about 0.09 to 0.12mm (.0035433" to 0.0047244") expansion after firing. No pressure signs when inspecting the primer so was wondering what is the normal expected range and when should I become alarmed? I guess the chamber dimensions will also have quite a bearing on expansion as well. Look forward to your considered advice and experience
Ruger7mm

Chamber dimensions are the primary factor, followed by case dimensions and hardness (they do vary slightly between manufacturers). What you have is nothing to be concerned about.

https://www.nzhuntingandshooting.co....sion-r8-55338/

Ive never got that far into it but if it was fl sized before you fired it id measure after that firing neck size case fire again and measure as it might just be chamber tollerance

Thanks guys, my measurements are with first fired cases, so will look for bugger all expansion with the next round of loads.
many thanks
7mm

Originally Posted by gundoc

Chamber dimensions are the primary factor, followed by case dimensions and hardness (they do vary slightly between manufacturers). What you have is nothing to be concerned about.

Drop a piece of new brass down a Tikka chamber, like a bloody sausage in a hallway.