Head Space (defined)?

[Just_me_mongo]

Hello all,

I am having a hard time visualizing/understanding the concept of headspace. Does anyone have a definition and or site that they can share? I would appreciate all/any input. Thanks!

[T2C]

For a rimless bottle neck cartridge, such as a .223 Rem., headspace is the distance between the back of the case to the datum line on the shoulder. The datum line is indicated on the diagram by the line with the arrow on it halfway down the taper near the case mouth. Straight wall cases headspace off the case mouth.

Good headspace allows the case to stretch within acceptable parameters during the firing sequence. Excessive headspace can permit a case to stretch too much and fail.

[ess45]

Or this.
Headspace for bottle-necked rimless cases is the dimension between the bolt face and the datum line on the chamber.

https://farm6.staticflickr.com/5321/9693761017_b622ccd7c8_b.jpg (https://flic.kr/p/fLB4qD)

[Just_me_mongo]

Ah, finally! Thank you guys!

So my next question: How is excessive headspace caused? Is this by turning your resizing dies in too far? Poor bolt specs?

[bigedp51]

A picture is worth a thousand words.

http://i122.photobucket.com/albums/o254/bigedp51/Headspace_2_lg_zps3fea821e.jpg
http://i122.photobucket.com/albums/o254/bigedp51/Headspace_1_lg_zpsdd7501b6.jpg

And head clearance is how much shorter the case is than the chamber and how far the case can stretch when fired.

http://i122.photobucket.com/albums/o254/bigedp51/HEADCLEARANCE-a_zps1a9a1011.jpg

http://i122.photobucket.com/albums/o254/bigedp51/HeadClearance_zpsf30a3af1.gif


http://i122.photobucket.com/albums/o254/bigedp51/shouldersetback_zps59bf1b04.jpg

The worst type of excess headspace is found in dimly lit bars and is caused by unscrupulous bartenders.

http://i122.photobucket.com/albums/o254/bigedp51/excessheadspace_zpsf2634b56.jpg

[Onyx Z]

Ah, finally! Thank you guys!

So my next question: How is excessive headspace caused? Is this by turning your resizing dies in too far? Poor bolt specs?

Excessive headspace is caused by sizing your brass too far down when it is to be used in an in-spec chamber. So yes, turning your resizing die in too far will cause excessive headspace on bottle neck cartridges.

[ess45]

Ah, finally! Thank you guys!

So my next question: How is excessive headspace caused? Is this by turning your resizing dies in too far? Poor bolt specs?

SAAMI definition of Headspace is the distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats.
So by SAAMI definition, headspace pertains to the chamber, not the cartridge.
https://farm6.staticflickr.com/5321/9693761017_b622ccd7c8_z.jpg (https://flic.kr/p/fLB4qD)


What then is the space between the datum line of the shoulder and base of the cartridge?
Let us just call it the X space for now.
https://farm1.staticflickr.com/480/19282335864_9b4994cf72_o.png (https://flic.kr/p/vnV1EC)

So by definition excessive headspace is a chamber that is reamed too deep.
If you chamber a SAAMI spec cartridge to a oversized chamber, what you have is an increase in head clearance.
HEAD CLEARANCE is defined as the distance between the base of a fully seated cartridge and the face of the bolt face when the action is in the closed position.



Turning in the resizing die too much will decrease the X space and when chambered, the head clearance is increased.
The recommended head clearance when sizing a brass are .003-.005 for semi auto and .001-.002 for bolt action. This is what bumping the shoulder is all about.
Too much head clearance will cause head separation and for negative head clearance, you will not be able to close the bolt.

[texasgunhand]

This is were the hornady headspace gauge comes in handy for setting up your dies. Not expensive but it works.

[colt933]

The terms 'headspace' and 'cartridge headspace' are sometimes mistakenly interchanged.

[bigedp51]

ess45

I have sent you a PM about my image you copied to your staticflicker account that you reused here. I made this image and it is not yours to copy and use, I made this image and other to help my fellow reloaders "BUT" you copied the image to your account and are using it like it belonged to you. There isn't room in this forum or any forum bigedp51 posts at and you reposting my material.

Below my link you copied from my photobucket image account.

http://i122.photobucket.com/albums/o254/bigedp51/HEADCLEARANCE-a_zps1a9a1011.jpg Please note my screen name is in the link, photobucket.com/albums/o254/bigedp51/HEADCLEARANCE-a)

And below my image transferred to your staticflicker account.

https://farm1.staticflickr.com/457/19716972388_36dea648bc_z.jpg

Bottom line delete any images you copied from me, there isn't room for both of us using my material in the same forums.

Headspace is also the distance between your ears and how you use it.

[colt933]

I don't see any pictures in my post and don't understand what you're talking about.

[colt933]

There are no messages from you in my inbox. I don't understand what you're talking about.

[colt933]

I don't know what statflicker is and don't have an account there.

[colt933]

I believe you have mistaken me for user ESS45 above.

[bigedp51]

I believe you have mistaken me for user ESS45 above.

I'm sorry, you are correct, I quoted the wrong link, again my apologies. I have edited my post to designate the correct copycat rat bastard lowlife commie Pinko pervert.

[markm]

So my next question: How is excessive headspace caused? Is this by turning your resizing dies in too far? Poor bolt specs?

As stated it can be caused by over sizing your brass. Secondly, it can be caused by wear on a high volume weapon. The bolt lugs peen the inside of the barrel extension and increase headspace. Poor bolt specs are almost unheard of.

[ess45]

ess45

I have sent you a PM about my image you copied to your staticflicker account that you reused here. I made this image and it is not yours to copy and use, I made this image and other to help my fellow reloaders "BUT" you copied the image to your account and are using it like it belonged to you. There isn't room in this forum or any forum bigedp51 posts at and you reposting my material.

Below my link you copied from my photobucket image account.

http://i122.photobucket.com/albums/o254/bigedp51/HEADCLEARANCE-a_zps1a9a1011.jpg Please note my screen name is in the link, photobucket.com/albums/o254/bigedp51/HEADCLEARANCE-a)

And below my image transferred to your staticflicker account.

https://farm1.staticflickr.com/457/19716972388_36dea648bc_z.jpg

Bottom line delete any images you copied from me, there isn't room for both of us using my material in the same forums.

Headspace is also the distance between your ears and how you use it.

Sorry about that.