Hornady Headspace Gauge

Some of you from the old site might have seen this video before that I made.



After having the video up for a little over a year now, I have had a member recently ask me several questions and I wanted to post them here for future reference and to get input from the knowledgeable members here.

Question 1:
what are you comparing the length to? Do you take a fireformed case and check the shoulder on it or do you take a new case and measure the headspace or do you look in a book for the max length and shorten it from there?

Answer 1:
In this video it was with a fireformed case from my rifle that I wanted to bump the shoulder back .001". You could also use the tool to measure new cases to make sure your die is setup correctly.

Question 2:
how can you use it to check your die to make sure it's set up correctly with new brass? Wouldn't new brass shoulders be further back than a fireformed case that has to be pushed back just .001?

Answer 2:
Hypothetically the shoulder on new brass should be further back than a fire-formed case, however new brass should always be resized before loading to verify proper chambering. Consistency equals accuracy, so the more uniform you can get your cases in all measurements will help.

This tool can help make sure you are not setting the shoulder too far back when resizing these new cases which could cause improper firing pin contact, help determine if the factory cases are somehow not uniform or out of SAAMI specs, compare new cases to fired cases which in turn could help determine if your chamber has excessive headspace, check for bent rims, etc.

The further back the shoulder is, or the more "sloppy" your chamber is, energy from the powder is being wasted on expanding the case walls to the chamber than launching the projectile.

Question 3:
when you said that you can use this device to check factory cases, how can you do that when there is a bullet in it? You couldn't use the headspace gauge nor do any type of full length resize with the bullet in it. Also what are signs of excessive headspace and how would you see that in the measurements? How I've always heard to worry about headspace was after 3 or 4 shots you check to see if the brass seats into the bolt and if it doesn't you push the shoulder back but this is also a problem because some of my bolts are hard to close on my older guns so I might force the bolt closed even though the shoulder is too high. My question to that is how do I know when I should push the shoulder back? Should I look at a one time firedformed brass or is there a easier way to make sure I have the best headspace just as I would if I pushed the shoulder back when the bolt wouldn't close?

Answer 3:
there is a hole in the middle of the insert that the case mouth and bullet can go through. checking factory cases would be more for checking before and after firing measurements to check how much the case stretched in firing. i personally keep records of all my after firing measurements for my particular rifle to see if the chamber starts to go.

[You must be registered and logged in to see this link.] here is a pretty good article explaining excessive headspace.

full length sizing dies set the shoulder back and resize the neck, neck sizing dies do not set the shoulder back and only resize the neck. So if you are only using neck sizing dies after 3 or 4 firing it becomes necessary to full length size because the shoulder has moved forward. the theory behind neck sizing is energy is not consumed expanding the case (since its already fireformed to your chamber) but launching the bullet.

if your bolt is hard to close that is a sign when you should push the shoulder back, or it could mean your full length sizing dies are not setup correctly ie not setting the shoulder back or setting it back enough. this tool would allow you to check this before you end up at the range with a bunch of rounds that wouldnt chamber. If you measure a one time fireformed case, that should give you your "base" measurement to adjust your die to bump the shoulder back a recommended .001" minimum for bolt or .003-.005" minimum for semi. Your rifle is going to determine this.

Question 4:
how can you push the shoulder back for semi autos? You usually have to do a full length resize anyway and that pushes the shoulder back for you so how could you use this headspace gauge for the semi autos? I guess what I'm also asking is how could you ONLY push the shoulder back partially?

Answer 4:
it is recommended to always use a FL sizing die when reloading for semi's as this is how you set the shoulder back for proper function & chambering. this is especially critical for weapons that have a floating firing pin as if it is headspaced wrong it increases the chances for a slamfire. this tool is for measuring only, it does not set the shoulder back or perform any sizing. there is no way to "partially" set the shoulder back, you either do or you dont.

So exactly what is it this member looking for? Does this person want to know what the SAMMI specs are for a brand new case to see where the shoulder should be?

I think I am getting lost in the questions being asked, but seems you have covered them with the answers I think lol...

I have never used this tool before and have no expierence with it to try to help. I will sit back here and watch this with great anticipation in hopes to learn something....

Great video.

Great vid!

Great tool for determining if your dies are doing what they are supposed to do.

Click here to see the video starting at 3:38
[You must be registered and logged in to see this link.]

Right at 3:40 you say that the headspace for your 22-250 case measures 1.566 inches.

The headspace for 22-250 is supposed to be 1.578. So you are off by 22 thousandths. The shoulder is back 22 thousandths more than it should be, right? So is that ok? Should you try to being just 3 or 4 thousands off? 22 thousandths sounds like a lot.

First, your measurement is wrong. Its 12 thousandths (1.578-1.566 = .012). *I don't mean to sound defensive*

Second, 1.578 is SAAMI’s recommended maximum length. Meaning if your bolt is closing on anything at that measurement or greater you may have excessive headspace. Forster's cartridge measurements (from shortest to longest) are 1.574" for Go, 1.579" for No-Go, and 1.583" for Field Gauge. Meaning my chamber is .008 under their minimum, which is in tolerance.

Third, I am measuring what my brass comes out of my rifle. So I’m not saying everyone with a 22-250 needs to set their shoulder at 1.563 (my measurement of 1.566 - .003).

What I am saying is to properly setup your die to allow for minimal clearance of your chamber, reduce case stretching and hardening of brass, you should set your shoulder back .001-.002 for bolt action and .003-.005 for a semi.

I don’t think I know anybody who likes making 100 rounds and going to the range to find they won’t chamber =)

Hello XbonesX,

I am starting to understand a little better after reading your reply 4 times. One mistake I was making is that I was acting like headspace is something that a cartridge has. But it is not, of course. Headspace is something that a gun has. I will keep working on getting the info to sink in. Thanks for taking the time to help me understand this.

So if you find that the shoulder is too far back what can you do about it? Is there a gadget that will push the shoulder back?

The shoulder will move forward again upon firing.

XbonesX wrote:The shoulder will move forward again upon firing.

Is that ok to do that? I was thinking I had read that bumped-back shoulder would allow the cartridge to scoot too far forward in the chamber and then the case head would be too far from the breech face and that that was bad, allowed the case to stretch when fired. Does that sound right? So maybe I should use a special load?

if you reduce your charge you can extend the bullet to keep that from happening.

how far back is your shoulder!?!?

all cases stretch when fired. they actually stretch in a curved manner, like a banana.