Thread: What happens to factory brass on first firing ?

Originally Posted by ebf

nope, above the groove with standard outside micrometer

Just looked up my data for my latest 308 Palma brass, once fired. Measured in the groove in 2 places.
Unfired 0.4053
Same case fired one time 0.4055
Would expect no change after next firing with the loads I am using.

Have seen more movement on other rifles after first firing and then nothing or very little (1/10 thou) with subsequent firings then dimishing to zero depending upon loads.

Did some checks on my 6.5 AI brass and that is more dramatic. 1.3 thou change, and reflected in the primer pocket expansion.
That's after 5 firings with a ripe-ish load.