Head spacing ?

[BrentM]

I have a Hornady headspace gage kit that I am using to measure hs on my cases. I have new, once fired, and multiple reloaded cases.

New unfired 1.832
1 x fired and neck sized 1.840
Fired and not sized 1.8415

Should I use the 1.840 for case shoulder set back or 1.838?

 

[varmintH8R]

1.839"

I've found different brass or different number of firings leads to (slightly) different fired measurements with my Hornady kit. I generally set up to bump 2 thou back from the measurement of the brass I am sizing.

I'm not sure if I am explaining that right, so here's an example:

Brass x reads 1.840. I'll set my body die to bump to 1.838.

If after the next firing the brass reads 1.841, I'll bump to 1.839.

I figure there has to be some inherent measurement error, the Hornady kit isn't "true" headspace, etc. As long as I am going 2 thou back from the measurement that just came out of the chamber, I assume I'll be OK. Haven't had an issue yet (FWIW).

 

[BrentM]

So, to be clear you set the shoulder back each time you reload? If so, does that mean you would consider my measure of 1.840 to be the max head space and set the die to set back to 1.838 and leave it?

 

[varmintH8R]

So, to be clear you set the shoulder back each time you reload? If so, does that mean you would consider my measure of 1.840 to be the max head space and set the die to set back to 1.838 and leave it?

Ha! I misread your original post and went on a long ramble where a short one would have done. Yes, I would bump back to 1.838 in your case.

I do bump shoulders every time I reload. Right now I use a redding body die and neck size separately. In the future I may go to a FL/bushing set-up. I am in the "always FL size" camp, but do my best to control both neck and body so I am not over-sizing.

 

[BrentM]

I have a redding body die as well. I am trying to develop a better SOP. Thanks for your input.

 

[Mikecr]

You should bump it back to no more than 2thou under fully fireformed.
1x firing probably didn't get you there yet. For my cartridges it takes at least 3 firings to get fully fireformed & that's when I start measuring & setting bump.

It seems odd to me that your shoulder would be pushed by neck sizing alone. Are you sizing the entire neck length? How much downsizing?
I doubt this push of the shoulders will hold over time, and would not count on this as a good number for bump adjustment unless it did.

 

[BrentM]

I didn't mean to imply neck sizing did anything. It really should not with minimal neck tension. Thanks for the info on the fire forming. Excellent feed back.