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Finding Head space??

FamilyMan

Sergeant
Full Member
Minuteman
Aug 3, 2011
720
0
Utah
I am setting my dies up to bump the shoulder back.002 on a bolt gun and was wondering if the size of the fired case after only 1 firing is enough to give an accurate headspace measurement? I thought I remember reading in the comments somewhere on here that it took a couple firings to achieve desired headspace but to me it seems like you could get it in the first firing hence the process of "fire forming".
 
Re: Finding Head space??

shoot in the same rifle some new cases one time, some others three times (same brand,same batch, same full reloads), measuring their headspaces before and after_nobody will answer it better than your own test_
 
Re: Finding Head space??

under the apparent roughness of my answer,stay the fact that,for a correct reply,we need know all the variables involved,and for sure you will have opposite answers from anyone even at this time_with a total amount of few reloads (three for one time,tree for three times),you will have the soundest answer_ good luck!
 
Re: Finding Head space??

There was nothing rough about your answer at all, just facts which i prefer. I just set aside a set of 20 brass to keep just for this Head space test. to see if i get anything different from 1st to 3rd firings.
 
Re: Finding Head space??

After a number of firings, your brass will start work harden and not "spring back" quite as much and will give you slightly different measurements.

I think measuring after each firing/re-sizing will be a good idea. It should give you a better idea how to set your dies as well as letting you know when it is time to anneal.
 
Re: Finding Head space??

I've noticed that as i lower the sizing die, the case gets longer as the walls are sized, and the shoulder length moves forward, before the die starts pushing back the shoulder. So I slowly turn in the die, sizing and closing the bolt on the sized case, and see how the case fits in the rifle. Once the bolt gets hard to close, I figure I have my headspace, and back off a little from that, and lock down the sizing die.
 
Re: Finding Head space??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ShtrRdy</div><div class="ubbcode-body">What do you use to measure the headspace of a fired case?
</div></div>
I use the Hornady tool with a digital caliper. I took 20 cases that were fired from the rifle and measured the headspace of each and then averaged them to get my headspace and then i set my die to bump it back .003-.002
If its worth anything rifle is rem700 SPS varmint .243
 
Re: Finding Head space??

Averaging anything simply injects irrelivant data into your work. Fired cases are already shorter than the chamber. For a bolt rifle, setting shoulders back any further than absolutely needed simply increases case stretching for no benefit. Measure the shoulder location on a box of fired stuff and set your sizer so the longest one is resized to put the shoulder back to the same location or a tad less, the rest will then be fine too.

Concern about resetting a die seems unnecessary, it's just not that hard to do.