Measure headspace with seating die

[Blancoalex]

Little trick to measure your rifle's headspace is to use seating die with bullet seater removed and die cleaned. I actually use cheap secondhand seating dies for this. My 308 Win covers all the 308 family cartridges. 243, 260, 7mm-08 and 308.

It will be good to have a headspace GO gauge also to give you a baseline measurement.

In pics you can see this. A real example is my one 243 Win loaded round measures 3.492" and fired case measures 3.495" which shows I had .003 clearance for this hunting rifle.

Or you can have your gunsmith make you a gauge with scrap barrel using same reamer he built your rifle with.

 

[bigedp51]

You can do the same thing with a Hornady cartridge case headspace gauge.

Below a "FIRED" case from my AR15 I then set the die up for .003 shoulder bump.

 

[rsmithsr]

EXCEPT this is NOT HEADSPACE.
headspace is a characteristic of the CHAMBER of a gun.
it is the distance from the bolt face to a datum line.
if a rimmed case this is trypically just a rim thickness ,
for everything else it is a reference point in the shoulder of the chamber. it is not "adjustable". it is set by the gunsmith when chambered( well except for current savage rifles)
what most of you are measuring is CASE CLEARANCE, and sizing to provide some clearance.
end of lecture

 

[bigedp51]

Headspace is also the distance between your ears and your ability to use this space.

If I say chamber headspace reloaders will understand that term. And if I say cartridge headspace they will also understand. And when I bought my Hornady case gauge it was labeled "Hornady Cartridge Case Headspace Gauge" and understood what Hornady was saying.

This is a reloading forum and not an English class where proper nouns must be used.

P.S. The term is not "case clearance" it is called "Head Clearance" which is approximately the amount of your shoulder bump. And normally you only want .001 to .002 of shoulder bump when sizing the case.

And at the extreme end a British Enfield rifle at max military headspace of .074 and a rim thickness of .058 you would have .016 head clearance.

 

[rsmithsr]

since you pointed out the error of my words I thought this to be useful:
head clearance
The distance between the head of a fully seated cartridge or shell and the face of the breech bolt when the action is in the closed position. Commonly confused with headspace.

straight from the saami glossary

 

[25WSM]

Oh I hope guffey doesn't see this thread. He will tell you he can measure headspace 3 ways without guages but won't tell you how. Headspace and head clearence is 2 different things. Your headspace is a fixed number and head clearence is created when we set shoulders back. Both terms get used interchangeably during reloading and we all know what it means proper or not. It's not a big deal to me and I build rifles. I just assume guys are talking About clearence when discussing reloading. Your actual headspace is irrelevant as long as your in spec. The head clearence is what's important.
Shep

 

[bigedp51]

Below a Colt 5.56 Field gauge at 1.4736.

Below the same Colt Field gauge in my Hornady Cartridge Case Headspace gauge. The red and silver sections were adjusted and separated .011 to get the same reading.

Below a "FIRED" case from my AR15 in my Hornady Cartridge Headspace Gauge and I'm not measuring "head clearance". This case is very close to actual chamber headspace minus brass spring back after firing. My sizing die is then set for .003 shoulder bump.

 

[bigedp51]

Below the cheap bastards headspace gauge.

Measure a case from the case mouth to the base of the case and write it down.

Next just using your fingers start a fired spent primer into the primer pocket.

Now chamber this test case and let the bolt face seat the primer and remove the case.

Next measure the case again from the case mouth to the base of the primer and write it down.

Now subtract the first case measurement from the second and this will be your actual head clearance.

If I measure this case in my adjusted Hornady Cartridge Case Headspace gauge it will tell me my chambers actual headspace. All a actual headspace gauge tells you is if the bolt closes or will not close.

Below a set of nine .308 headspace gauges in .001 increments that gets you closer to actual chamber headspace.

And since I'm a cheap bastard a case and a fired primer is cheaper than headspace gauges and tells you more.

 

[Coldfinger]

So as long as everyone is correcting each other what do the pros think of using a resized case for a go gauge?

 

[bigedp51]

So as long as everyone is correcting each other what do the pros think of using a resized case for a go gauge?

Chambers and dies vary in size so a resized case could "NEVER" be used as a GO gauge.

At SavageShooters.com you see people changing barrels and using a new case and pieces of scotch tape to make a GO gauge. Their next posting is "Help my resized cases will not fit in my chamber". Meaning they set the headspace too tight and their die does not push the shoulder back far enough.

If you look at a SAAMI cartridge and chamber drawing it lists most standard cartridge cases with Min and Max headspace with .010 between the two. Meaning the GO and NO-GO gauges are used to set headspace on new rifles or when replacing a barrel. And if the bolt closes on the NO-GO gauge it does not mean you have excessive headspace.

Below depending how far up or down the sizing die is adjusted it is possible to make the case "LONGER" than the chamber. And if the die is adjusted to make hard contact with the shell holder you can push the shoulder back too far and create excessive head clearance. In simple terms, you only want to bump the shoulder back approximately .002 below the red dotted line in the image below.

In my opinion, the Hornady Cartridge Case Headspace Gauge is the best tool to measure fired cases. And then adjust the die for minimum shoulder bump for your type rifle. The best part about the Hornady gauge is you only need to buy one gauge for every caliber rifle you have.


Pacific Tool and Gauge offers three lengths of headspace gauges per rifle caliber. In order from the shortest to longest, they are: GO, NO-GO, and FIELD:

GO: Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gauge, the chamber will accept ammunition that is made to SAAMI's maximum specifications. The GO gauge is essential for checking a newly-reamed chamber in order to ensure a tight, accurate and safe chamber that will accept SAAMI maximum ammo. Although the GO gauge is necessary for a gunsmith or armorer, it usually has fewer applications for the collector or surplus firearms purchaser.

NO-GO: Corresponds to the maximum headspace Forster recommends for gunsmiths chambering new, bolt action rifles. This is NOT a SAAMI-maximum measurement. If a rifle closes on a NO-GO gauge, it may still be within SAAMI specifications or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gauge. The NO-GO gauge is a valuable tool for checking a newly-reamed chamber in order to ensure a tight and accurate chamber.

FIELD: Corresponds to the longest safe headspace. If a rifle closes on a FIELD gauge, its chamber is dangerously close to, or longer than, SAAMI's specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith. FIELD gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin.

 

[elimsprint]

[Q

At SavageShooters.com you see people changing barrels and using a new case and pieces of scotch tape to make a GO gauge. Their next posting is "Help my resized cases will not fit in my chamber". Meaning they set the headspace too tight and their die does not push the shoulder back far enough.

I don't know where you got the "use a new case" from. I read there long ago to use a full length resized case with a piece of scotch tape on it to set headspace and then your headspace matches your dies. It's worked just fine for me for the 5 guns I have done it on.

 

[Coldfinger]

[Q


I don't know where you got the "use a new case" from. I read there long ago to use a full length resized case with a piece of scotch tape on it to set headspace and then your headspace matches your dies. It's worked just fine for me for the 5 guns I have done it on.

That's what I meant I used a new case run thru a full length resizer. It's worked fine for me on several builds. Had a Canadian smith tell me to just bump case or gauge and he called it zero headspace.

 

[rsmithsr]

do not worry, eddie will come back with charts and graphs to prove his OPINION.

[Q


I don't know where you got the "use a new case" from. I read there long ago to use a full length resized case with a piece of scotch tape on it to set headspace and then your headspace matches your dies. It's worked just fine for me for the 5 guns I have done it on.

 

[bigedp51]

If you use a fired case vs a GO gauge you do not know how much the case will spring back after sizing. Then you add scotch tape to the base of the case with its squish factor. Meaning the resized case and tape are not what I would call a precision gauge.

But normally you have approximately .003 between the GO and NO-GO gauges. Meaning your resized case and the scotch tape "may" be good enough for you. "BUT" if you look at all the variations in dies and scotch tape thickness it is a very ballpark guesstimate of actual headspace.

And if you are replacing the barrel this means the resized case was not fired in the chamber of your new barrel. Meaning that case was fire formed for a different chamber and you have no idea how much the case will spring back after sizing.

Bottom line, buy or rent GO and NO-GO gauges to setup the headspace and not rely on scotch tape made in China.