I've got the Hornady headspace gauge kit. I'm trying to resize the bag of once fired .223 rem I got. (Second time I've ever reloaded, and first time by myself). I set it up according to Lee's little pamphlet that came with the due kit. I got about 10 cases run through it when I decided it'd make sense to try the fit on my AR. The bolt locked, but it was really quite hard to extract. I got the SAAMI spec, and the case was 1.459. The problem I found was the Hornady gauge is not .330. Mine is .327 making the headspace measurement off by .0035. I guess I'll have to set my dial caliper up -.004 now. Anyway, how do you guys decide what to set your headspace to for an AR? I found some cases that are below the SAAMI spec too. What do you do if you get one that is 1.448? Shoot it and resize it again?
Headspace gauge off?
- Thread starter Islandboy
- Start date
CatShooter
Islandboy said:
All the Hornady headspace gauges are off - some dummy at the factory counter sinks the bore hole to remove the burr
You need a real (steel) headspace gauge to zero the Hornady gauge so you can make real measurements - BigEdP51 had some nice photos - PM him and he will gladly post them on how to do it!
stool
you are talking case clearance, not headspace.
headspace is a characteristic of a chamber and bolt face, and has nothing to do with brass.
case clearance is determined from a given chamber. regardless of its headspace.
the hornady , and similar tools measure chamber to brass clearance, not chamber headspace.
headspace is a characteristic of a chamber and bolt face, and has nothing to do with brass.
case clearance is determined from a given chamber. regardless of its headspace.
the hornady , and similar tools measure chamber to brass clearance, not chamber headspace.
bigedp51
If you are adjusting you dies for shoulder bump all you do is measure a fired case from your AR15 and bump your shoulder back approximately .003.
The Hornady cartridge case headspace gauge is a comparator gauge and if you do not have a real headspace gauge it can not be adjusted to read actual headspace.
If you have once fired brass fired in another AR15 rifle then you should resize these cases to minimum. All my once fired brass is resized in a small base die to insure minimum dimensions. Then after firing in my rifles a normal .223/5.56 full length die is used.
Do not forget the brass tries to spring back after sizing and you should pause at the top of the ram stroke for three seconds when sizing range pickup once fired brass.
All full length dies should make your resized case shorter than the GO gauge until the die is adjusted for proper shoulder bump. I'm loading for three different AR15 rifes, the plus .004 shell holder below will size my cases to the GO gauge or approximately 1.464.
Below a Colt 5.56 Field gauge, 1.4736
Below the Colt field gauge in my adjusted Hornady gauge.
Below the average fired length before sizing, NOTE, the brass has spring back after firing and the length below is at the SAAMI NO-GO limits and many fired cases were longer than this.
Below the same case after .003 shoulder bump. (and GO gauge length)
Below a new unfired Federal M193 cartridge and .002 shorter than the GO gauge.
Also if you have a 5.56 chamber the SAAMI doesn't set military headspace limits and your chamber headspace will most likely be longer than the SAAMI NO-GO gauge.
Measure a new once fired case fired from your AR15 to adjust your shoulder bump .003 to .006 shorter. If you do a little math you will see the new unfired Federal case above is .005 shorter than my fired length and brass springback is not figured in.
The Hornady cartridge case headspace gauge is a comparator gauge and if you do not have a real headspace gauge it can not be adjusted to read actual headspace.
If you have once fired brass fired in another AR15 rifle then you should resize these cases to minimum. All my once fired brass is resized in a small base die to insure minimum dimensions. Then after firing in my rifles a normal .223/5.56 full length die is used.
Do not forget the brass tries to spring back after sizing and you should pause at the top of the ram stroke for three seconds when sizing range pickup once fired brass.
All full length dies should make your resized case shorter than the GO gauge until the die is adjusted for proper shoulder bump. I'm loading for three different AR15 rifes, the plus .004 shell holder below will size my cases to the GO gauge or approximately 1.464.
Below a Colt 5.56 Field gauge, 1.4736
Below the Colt field gauge in my adjusted Hornady gauge.
Below the average fired length before sizing, NOTE, the brass has spring back after firing and the length below is at the SAAMI NO-GO limits and many fired cases were longer than this.
Below the same case after .003 shoulder bump. (and GO gauge length)
Below a new unfired Federal M193 cartridge and .002 shorter than the GO gauge.
Also if you have a 5.56 chamber the SAAMI doesn't set military headspace limits and your chamber headspace will most likely be longer than the SAAMI NO-GO gauge.
Measure a new once fired case fired from your AR15 to adjust your shoulder bump .003 to .006 shorter. If you do a little math you will see the new unfired Federal case above is .005 shorter than my fired length and brass springback is not figured in.
CatShooter
stool said:
Not true... SAAMI sets specifications for chambers and brass - they are published data.
bigedp51
stool said:
If you take a fired spent primer and just start the primer into the primer pocket and use the bolt to seat the primer as you close the bolt you can measure actual chamber headspace.
On a resized case the head clearance is the same measurement as your shoulder bump.
bigedp51
CatShooter said:
Bazinga
"The SAAMI suggests cartridge and chamber guidelines"
As an example the throat on my factory Savage .223 is LONGER than the throat on my AR15 rifles.
Sorry CatShooter its March madness and your scoring bracket was off.
And my little friend doesn't like your name and made me do it.
CatShooter
bigedp51 said:CatShooter said:
Bazinga
"The SAAMI suggests cartridge and chamber guidelines"
As an example the throat on my factory Savage .223 is LONGER than the throat on my AR15 rifles.
Sorry CatShooter its March madness and your scoring bracket was off.
And my little friend doesn't like your name and made me do it.
Your fuzzy little friend is safe so far (but is is getting a little shakie)...
... but your March Madness is off.
My comment was in reply to Stool's comment that SAAMI sets chambers, but not brass - they set both - it is not law, and SAAMI compliance is "voluntary, but the standards are there for anyone, or any manufacturer to see.
(Kitty, BITE that badd man!!)
CatShooter said:
My "Kitty" ( a 22# Orange Tabby/Maine Coon mix) doesn't need to bite when it lays in my lap like that. I've learned that you don't want the cat to be startled. When it launches itself from your lap, for some reason the "family jewells" always end up providing "traction" for it's rear claws. Damn that hurts
stool
one last time....
HEADSPACE IS A CHARACTERISTIC OF A CHAMBER AND BOLT..
SAMMI CASE size is just that CASE SIZE.it is not HEADSPACE.
THE DIFFERENCE IN CHAMBER SIZE AND BRASS SIZE IS CALLED ......."clearance"
GO READ WHAT I SAID...
your "not true" is improperly placed......as i never said they did or did not
HEADSPACE IS A CHARACTERISTIC OF A CHAMBER AND BOLT..
SAMMI CASE size is just that CASE SIZE.it is not HEADSPACE.
THE DIFFERENCE IN CHAMBER SIZE AND BRASS SIZE IS CALLED ......."clearance"
GO READ WHAT I SAID...
your "not true" is improperly placed......as i never said they did or did not
CatShooter said:
I gave this method a try. I like this to start off with so that I don't have Togo to the range just for a fired casing. It gives me a quick n dirty starting point. I got 1.458 4 times in a row with my calipers zeroed. If I correct for the screwed up bore diameter of it by subtracting 0.0035-0.004 I got 1.455. Either way those numbers seem yo fit SAAMI specs. So, I guess now I know I need to bump the shoulder back about 0.003 more, take trip to the range to do the rifle break in and clean, and gi reform my brass.bigedp51 said:stool said:
If you take a fired spent primer and just start the primer into the primer pocket and use the bolt to seat the primer as you close the bolt you can measure actual chamber headspace.
On a resized case the head clearance is the same measurement as your shoulder bump.
bigedp51
amlevin said:My "Kitty" ( a 22# Orange Tabby/Maine Coon mix) doesn't need to bite when it lays in my lap like that. I've learned that you don't want the cat to be startled. When it launches itself from your lap, for some reason the "family jewells" always end up providing "traction" for it's rear claws. Damn that hurts
amlevin
I have a book you need to read.....................
"The Revenge of the Cat"
by Claude Balls
BoydAllen
Gold $$ Contributor
The simple fact is that Hornady has mislabeled the tool. It is a comparator pure and simple. If you have a gauge, you can use it in combination with the comparator to look at the dimensions of fired and sized brass, but even so, if cases are only once fired after having been loaded to the proper clearance and pressure for a semiautomatic rifle they are almost guaranteed not to reach the full datum line to bolt face dimension of the rifle that they were fired in.
I like your method of using the bolt to seat a primer, and think that it shows good problem solving ability. It is the first time that I have heard of it being done that way and just for fun, I am going to play with the method with a bolt action, just to get the feel of how reliable it seems to be.
Normally for a bolt rifle, I just neck size and fire a case several times with a stout load, and monitor the datum to head dimension to see when it stops increasing. I bump from that dimension.
We talk about case headspace but of course that is a misnomer, what we are really concerned with is clearance. Sometimes, when purposely misusing the term I put it in quotes like this ... case "headspace". I know the difference but sometimes it is faster to go with what is understood, using punctuation to denote the improper use of the term, than to stop and teach a mini-lesson on the proper definitions.
I like your method of using the bolt to seat a primer, and think that it shows good problem solving ability. It is the first time that I have heard of it being done that way and just for fun, I am going to play with the method with a bolt action, just to get the feel of how reliable it seems to be.
Normally for a bolt rifle, I just neck size and fire a case several times with a stout load, and monitor the datum to head dimension to see when it stops increasing. I bump from that dimension.
We talk about case headspace but of course that is a misnomer, what we are really concerned with is clearance. Sometimes, when purposely misusing the term I put it in quotes like this ... case "headspace". I know the difference but sometimes it is faster to go with what is understood, using punctuation to denote the improper use of the term, than to stop and teach a mini-lesson on the proper definitions.
bigedp51
One of the first examples of using a case to find your chamber headspace I saw was by cutting a case in half near the base of the case and cutting another 1/4 of an inch off the top part of the case. Then a copper bore brush that would fit snugly in the upper half of the case was epoxied in the base of the case after being screwed into the primer flash hole.
After the epoxy dried the top half of the case was slid over the bore brush, the top part of the case was pushed onto the bore brush leaving a 1/2 to 3/4 of an inch gap between the base and top part of the case. Now this test case was chambered and the bolt closed thus pushing the top part of the case back over the bore brush until the bolt was fully closed.
The test case was removed and placed in a comparator gauge and measured and this was the zero base line for shoulder bump.
I found it easier to use the primer method for different calibers rather than making separate bore brush gauges.
In milsurp forums where many people do not have headspace gauges the primer method was a good way to find your head clearance and get your correct shoulder bump without any gauges.
After the epoxy dried the top half of the case was slid over the bore brush, the top part of the case was pushed onto the bore brush leaving a 1/2 to 3/4 of an inch gap between the base and top part of the case. Now this test case was chambered and the bolt closed thus pushing the top part of the case back over the bore brush until the bolt was fully closed.
The test case was removed and placed in a comparator gauge and measured and this was the zero base line for shoulder bump.
I found it easier to use the primer method for different calibers rather than making separate bore brush gauges.
In milsurp forums where many people do not have headspace gauges the primer method was a good way to find your head clearance and get your correct shoulder bump without any gauges.
bigedp51
Nomad47 said:You are correct as usual, Boyd. And very diplomatic, I might add. We all knew what the OP meant and chose not to correct him - except for one caustic individual, who shall remain nameless.
PS. I think his last name is Sample.
Boyd Allen is always correct and proves headspace is also the distance between your ears and how well you use it.
I have both the Hornady headspace comparator and a Whidden comparator. If I use the Whidden and bump to a .001 set back, the hornady gauge still reads the same measurement. It takes .006 set back (clearance) as measured on the Whidden comparator to get the Hornady comparator to measure .001 setback. I tested to see which one was correct by resizing a case and closing the bolt. I resized and checked several times, the first few times the Whidden said the case was growing, and the bolt was stiff to close, but when the Whidden measured .001 set back, the bolt closed easily and the Hornady was still reading the same number.
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