Varying headspace

[DrJeckyl]

Is it normal for formed brass, 3-4 firings to vary in headspace measurements as much as .004?

Generally my measurements are 1.624 to 1.628, mainly around 1.627 but when deciding how much bump to give it's hard to tell, every so often I get a case with an extreme in measurement.

I did take one of the longer pieces and darkened the shoulder with a sharpie and the cases that measure 1.628-1.6285 I can see a mark on the shoulder so I have been trying to size to 1.626 figuring i'm getting a .002 bump, is this correct?

I'm using the Hornady headspace gauge and there's no buildup of gunk on the collet or the brass.

 

[janderson0]

Has all the brass been loaded the same each time? There has been some posts in the past months about work harding and how it effects bump. I find that even on the same batch of brass a difference in measurement, but only .001 and maybe close to .002.

Jim

 

[fdshuster]

Yes, I'll get some varience on headspace readings also, using the Stoney Point/Hornady gauge, although .004" is the maximum I've seen. .002" is the normal "maximum". Probably a result of the age/ number of reloadings with that particular piece of brass. Varying amounts of springback due to work hardening?

 

[BoydAllen]

Remember to knock out the fired primer before measuring as fired headspace on a case, to eliminate any inaccuracy caused by cratering.