Wheres your headspace?

[sailhertoo]

Is the extra room in the chamber in front of or in back of the cartridge?

In other words does the spring loaded <span style="color: #FF0000">ejecter</span> keep the brass pushed as far forward as it will go <span style="color: #000099">OR</span>

does the <span style="color: #FF0000">extractor</span> keep the brass tight to the bolt face with any slop then in the front?

This is a real conundrome for me.

 

[Agent Ronin]

Re: Wheres your headspace?

It really doesnt matter, because when the cartridge is fired. The force pushes the head of the case against the bolt face. The excess headspace is in the shoulder area, which the brass is forced to stretch and fill the void. Too much stretching or poorly setup resizing dies (FL) make for short life or head separations.

The short answer is, the headspace "gap" for a bottleneck case is the shoulder area. For straight walled cases its at the mouth. For rimmed, well the rim.

 

[dmgreene]

Re: Wheres your headspace?

There's also the school of thought that the firing pin drives the case forward upon impact and the web of the case is driven back by expanding gases which causes the the case head to separate instead of at the shoulder. Which one is correct, I don't have clue. As long as you're reloading just adjust die to fit your chamber and don't worry about.

 

[bigwheeler]

Re: Wheres your headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dmg264</div><div class="ubbcode-body">There's also the school of thought that the firing pin drives the case forward upon impact and the web of the case is driven back by expanding gases which causes the the case head to separate instead of at the shoulder. Which one is correct, I don't have clue. As long as you're reloading just adjust die to fit your chamber and don't worry about. </div></div>

This is the correct answer in most cases. The case thins in front of the head as
it stretches rearward. Repeated sizings and stretching eventually causes head separation. It takes roughly 4 times the pressure to expand the case in diameter as it
does to stretch in linearly. So first the primer unseats, then the case stretches back reseating the primer, then in grows in diameter each time the gun is fired.
So the experts say anyway.

 

[former naval person]

Re: Wheres your headspace?

And, if you have a sloppy chamber, the spring loaded ejector pushes the brass off center against the opposite side of the chamber...when fired, it stretches more on the long side and causes the base of the case to be off center...leaning if you were to stand it up on the base. This can and does cause future rounds to be off center and more inaccurate, and the misaligned base is unable to be corrected in reloading, at least that is my impression. That is one reason the bench rest crowd uses ejectorless actions (keeps brass on the bench too). Just another reason to have a good chamber done. (Especially at the price of brass now days!)

 

[sailhertoo]

Re: Wheres your headspace?

Thanks for all the good replys.

I'm just trying to nail down this loading to the lands bit and it <span style="color: #FF0000">all</span> depends on where your headspace "slop" is to begin with.

Thanks again