Head space

[Rifleman51]

I'll start off by saying I have not read all 5 pages of this post, I just want to give my 2 cents.

I'm a retired gunsmith and I always used a headspace guage, never a cartridge.

Reason is there are just too may different thicknesses of case heads or positions of belts.

I would headspace them tight, but it was always with a guage.

That way I knew every gun I built was the same. I always had reports of outstanding accuracy from my customers.
I just think it's the best way to do it. It takes away the variables with the exception of how tight you set your headspace from the feel of the bolt.
I knew the exact amout of resistance I wanted from my bolt on the HS guage and set each gun up with that amount of resistance.

One other thing. For a gun that is for benchrest shooting, tight headspace is a good thing.
If your hunting dangerous game, set the headspace looser. You still want it within the range of Go-No Go, but you don't want it really tight. This is for safety reasons. You want to be sure a bolt will close fast and if there is any dirt or grime on the case head or belt if it's a belted mag, the bolt will still close on it. You don't need .3" groups when shooting dangerous game, it's plenty big enough to hit with a rifle that shoots 1 to 2 inches at 100 yds.

John K

[Black Jaque Janaviac]

Dang. Now this thread has me wondering...

I measured the head gap clearance by adding layer of tape to a F.L. sized case until bolt refused to close. Then measuring the OAL length of the case with and without the tape. I got 0.030" of gap between case head and bolt face. I'm a bit puzzled though because I could feel the bolt closing harder much earlier, but didn't get "refusal" until 0.030". And even at that I think I might have been able to force it to close without much effort.

Is that too much for a .35 Whelen?

I then measured my .357 leverguns on got 0.007" gap on one and 0.020" gap on the other.

The levergun with a 0.020" gap has given me case head separation problems, although the Whelen has not yet separated a case. Now that could be entirely because the Whelen doesn't get shot anywhere near as often as the .357 does. In fact of my Whelen brass I doubt I've even reloaded one brass more than 10 times yet.

I did however have a failure to fire on my Whelen this year. I pulled the trigger and "click" but no "boom". I chambered a new shell and got the deer. The failed shell had no primer dent whatsoever.

Any thoughts?

[bigedp51]

How do you calibrate tape, how much does tape compress and how many companies sell headspace tape for checking headspace?

Use a spent primer and a new cartridge case to measure your head gap clearance. Measure the length of the case without the primer and write it down.

Seat the fired primer in the primer pocket just using your fingers just starting the primer into the primer pocket.

Chamber this test cartridge slowly closing the bolt, extract the case and remeasure the case and write it down.

Subtract the first case measurement from the second case measurement and the difference will be head gap clearance or the air space between the bolt face and the rear of the case.

Masking tape can be anywhere between .003 and .007 in thickness and 3M scotch tape has a .0015 backing with a total thickness of .0023 to .00246 with the adhesive included. Please note if you buy "other brands" like Chinese scotch tape you can forget the measurements or thicknesses above so "WHY" guess with scotch tape when you can use a set of vernier calipers and get the exact measurement.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0704.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0706.jpg

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0710.jpg

[Dirk]

You are not measuring headspace at all. What you are measuring is C.O.A.L. (cartridge over all length). Headspace is measured from the bolt face to a datum line on the shoulder of the chamber. You are measuring to the mouth of the case. Do it correctly and use GAGES! They are precision measuring devices, not soft brass.

[bigedp51]

You are not measuring headspace at all. What you are measuring is C.O.A.L. (cartridge over all length). Headspace is measured from the bolt face to a datum line on the shoulder of the chamber. You are measuring to the mouth of the case. Do it correctly and use GAGES! They are precision measuring devices, not soft brass.


Its is called measuring head gap clearance and "headspace" would be the length of the cases to the datum line "PLUS" head gap clearance.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP7212.jpg

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

Head gap clearance is the amount the primer protrudes from the rear of the case.

http://i122.photobucket.com/albums/o254/bigedp51/9-3.jpg

If you add rim thickness to head gap clearance you have your total "HEADSPACE" measurement.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP0727.jpg

Headspace is a numerical measurement, head gap clearance is what causes case head separations.

[bigedp51]

All a headspace gauge will tell you is if the bolt will or will not close on the gauge. ;)

Below is a Go gauge for a .243 Winchester and it is 1.630 long and the bolt on my Stevens 200 will close on this gauge. With the RCBS Precision Mic, an empty unfired case and a fired spent primer I was able to get the exact headspace measurement of my new Stevens 200.

The case measures 1.627 and the primer protrudes .004, the headspace of my Stevens 200 .243 is 1.631 or .001 over minimum headspace.

P.S. C.O.A.L or "Cartridge overall length" is the distance I use to seat my bullets from the lands. ;)
And C.O.A.L has nothing to do with headspace or head gap clearance. ::)

http://i122.photobucket.com/albums/o254/bigedp51/IMGP7241.jpg

Head gap clearance is what causes case head separations. (Rimmed .303 British cartridge below)

http://i122.photobucket.com/albums/o254/bigedp51/headspacestretch-1.gif

The less head gap clearance you have the less case stretching in the web area you will have "AND" the longer your brass will last.

http://i122.photobucket.com/albums/o254/bigedp51/f55-movie-dsf1.gif

Its funny what a old used primer can tell you if you know how to use it. ;)


Below head gap clearance in motion, red areas are maximum stress and stretch locations.

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

[DougMH]

So, I go out and buy a new barrel from <your barrel mfgr&#39;s name goes here>. I buy a GO/NO GO headspace set from <your headspace gauge mfgr&#39;s name goes here>. These gauges are made to precise .308 (in my case) standards.

If mate my barrel to the action and adjust for these precision gauges (bolt closes on GO and doesn&#39;t close on NO GO before and after final tightening), and the headspace is off in some way when I stick real ammo in there, the gunsmith who chambered the barrel is the the problem right?

I think if I had rounds that were created from fire-formed cases shot in an old barrel, I would never think of using them to gauge and/or fire in a new barrel. I would only create and fire full-lengh resized brass in a new barrel and continually monitor the dimensions of the ejected casings. If I was satisfied with those dimensions, I might then consider using fire-formed, neck sized cases.

[sharptailhunter]

Don&#39;t ya just love multi-paged topics ;D

So, I will be replacing the recoil lug on my model 12FV since I am putting an aftermarket stock on it I want a machined lug and not a stamped one, as I might glass bed the new stock. I may have the barrel flutted at that time as well, so it may be coming off and going back on, thus I have been researching the process of removing and reinstalling a barrel on the Savage action. Obviously, this would be my first time. So, here is what I&#39;ve gathered from all the previously posted material.
1. The go/no-go guages appear to be simple, some like em, some don&#39;t.
2. Bigedp51, I understand your method and I think it&#39;s what I&#39;m going to use, sort of....
3. Dirk, I see where you could claim that bigedp51 is only measuring overall CASE length, so....
4. I have to wonder, why hasn&#39;t anyone mentioned using a headspace measuring tool such as the one formerly made by Stoney Point, now sold under Hornady? At least it measures on the shoulder, where my cartridge, .204 Ruger, does headspace. http://www.hornady.com/store/Lock-N-Load-Headspace-Kit-With-Body-1-Each/ I already have this tool as I use it to measure how far back I&#39;m "bumping" the shoulder with my reloading dies.

So, I think this is what I&#39;m going to do:
1. Using the Hornady LnL headspace guage and a new case or a full length sized, I can get a starting overall measurement of the case, BUT, it would be measured on the shoulder (using the LnL gauge)... where it should be measured anyway. Now, that number is saved, and incidentaly, it could be any arbitrary number.
2. Add shims made from cut feeler guages (I agree that tape can be compressed and maybe isn&#39;t the right tool for the job when there are better materials out there) to the already measured case to get a new measurement, or number if you will, that would incorporate the case length and the correct amount of headspace to be desired.
3. Using the new new case, seat the barrel into the receiver until it stops on the case, then lock it down and try the standard tests.

My questions are these:
1. Does anybody see a reasson why this wouldn&#39;t work?
2. For a varmint hunting rifle, what would be an ideal headspace? Bare in mind, I need a reliable gun that will cycle the next round in case I get a hard charging rock chuck or prairie dog! ;) Of course, I&#39;m joking about the charging varmint.

[rsbhunter]

A charging varmint is nothing to joke about!!!!!!!!!!!!!! Had a friend mauled by a ground squirrel!!! it was awful!!!! but seriously, i am building a 6xc , so, if i buy new brass, can i use it to headspace off of, using feeler gauges cut, and also i have a 260 AI that i&#39;m building...i can&#39;t get formed case to use, can i headspace off of the 260 case? Sorry if this is hijacking, didn&#39;t want to start another 5 pager...Thanks, rsbhunter

[Dirk]

Buy the proper headspace gages!

[hotbrass]

Or pay a gunsmith to do it!

[Burnin-Powder]

I have a question, and i thought this headspace thing was where to ask it. I&#39;m new to all of this so bear with me if i ask a stupid question. Does head space really matter when setting a new barrel, or is it just for factory ammo? Eg. if i don&#39;t screw the barrel down far enough can i just seat a long bullet and let it fireform to the chamber then when i resize just don&#39;t bump back the shoulder? Like when AI forming brass wont it just be longer w/o the 40degree shoulder?My question is does it matter or will you just get a longer round with a shorter neck?Just asking?

[Dirk]

Yes that will stretch the brass. It could stretch it until it breaks (head separation) and releases gas into the action and at your face!

[vern748]

Hi All,

I am new at this barrel change thing, so let me know if I am going in the correct direction or not.

Just replaced the barrel on my 110 to a Varmint style. I have a Go/No Go gauge. That came with the kit. Here is what I did;
I used the gauges to set what I thought was the correct head space.
Using fried brass from this weapon and the bolt was tight, too tight, some did not close.
Used unfired, never used brass and the bolt was still tight, but did close.
Something wrong ??!!!

Took out my brand new ( 100 rounds ) 700 sps varmint in the same caliber.
Used fired brass from the Savage and it closed fairly easy, very slight drag
Used unfired, never used brass and the bolt closed nicely

Release the nut on the Savage and increased head space ever so slightly, but to make it similar to the feel of the Remington.
I kept just slightly more drag on the Savage.
The Go an No Go still worked as expected.

Was it too tight to begin with ? Is what I did incorrect.

Looking for guidance.

[Dirk]

Vern,

You did good and exactly correct. I&#39;d say you are go to go.

[bigedp51]

If the bolt would close on the GO gauge or minimum head space and not close on the NO-GO gauge you are under maximum and over minimum. (Or in the ballpark)

The last new 100 .243 cases I purchased were anywhere from minus - .001 to .009 or shorter than minimum head space. Fired cases were plus + .002 over GO or minimum head space.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP7241.jpg

As you can see there was maximum of .009 difference from the new cartridge cases and the go gauge, "WHY" would you use a new cartridge case of unknown length to check head space. Why would you use another rifle of unknown head space to judge the rifle you are working on. Also if you were just installing the barrel "where" did the fired brass come from???

A RCBS Precision Mic could be used to get much better readings of your cases using the GO gauge as reference "Zero".

Bottom line, you can&#39;t use a cartridge case to check head space if you do not know how long the case actually is.


Example below, this new unfired case is .006 "UNDER" minimum head space (GO) and should "NOT" be used to set your head space.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP7214.jpg

Simple ways to adjust for your rifles head space setting for anything over minimum or GO.

http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054345PM.jpg

http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054719PM.jpg

[vern748]

"WHY" would you use a new cartridge case of unknown length to check head space.
Why would you use another rifle of unknown head space to judge the rifle you are working on.
Also if you were just installing the barrel "where" did the fired brass come from???


Not sure if these are rhetorical questions but figured your information may be educational for anyone else in my situation.

"WHY" would you use a new cartridge case of unknown length to check head space.
A new cartridge will be of fairly standard length or a length that will fit into the standard chamber of a standard weapon. What good is purchasing a cartridge if it does not fit into the weapon it was designed to fit. It is does not fit my newly head spaced weapon it is either 1 of 2 problems ;

The cartridge is too long - maybe
or
My Headspace is too tight - more likely

Why would you use another rifle of unknown head space to judge the rifle you are working on.
If a new round chambered, cycled, and behaved nicely in a brand new, ie, just received my rebate check from Remington last week, then its highly likely that the head space is pretty good, or good enough to pass Remington&#39;s internal QA controls, in addition, it did not blow up on me when I shot it. In my limited opinion, this is a pretty good reference.

Also if you were just installing the barrel "where" did the fired brass come from???
I pick up my own brass. I clean and size my own brass. I can tell you when and how many times the brass was shot and what was the load for each of my Tupperware containers that I have my brass in. The fired brass was from the Savage 110 with the older barrel and the new Remington. The Savage fired brass was longer than the Remington.
The new brass is brand spanking new from Lapua.

My reason for adding to this thread was my impression that even when I did it correctly, by the book using the GO/NoGO gauge, the head space appeared to be too tight. Using additional "Tool" at my disposal, Used Brass, New Brass, New Rifle, and also the GO/NoGO gauges, I think I got the fit correct. You may disagree, and I do appreciate any feedback.

[Kurtinokc]

I need a bit of help.
My go no-go gauges came in today! As I was opening the box it hit me...i don&#39;t think they are going to work. It is a 7mm mag the gauges I bought use the belt for head space.... I don&#39;t load that way I just neck size.
But I need to fire form brass for the new barrel&#39;s chamber anyway so maybe sering it that way be ok after all.

[bigedp51]

For the last 10 years I been collecting and shooting milsurp Enfield rifles, these rifles have removable bolt heads and the headspace can be adjusted. The Enfield headspace settings are .064 min and .074 max and I have set the headspace from .005 under minimum and .010 over maximum testing headspace results with American made cases.

GO or minimum headspace is the "zero" reference point, this "zero" point isn&#39;t written in stone if your a reloader. BUT if you set the headspace tighter you take a chance that a new cartridge will not fit the chamber and also the chance your full length resizing die wont push the shoulder back when resizing.

Tight headspace keeps your cases from stretching and aids in accuracy, but remember this, a rifle that has headspace .010 over GO or minimum doesn&#39;t mean the rifle is a dog. Proper fireforming ensures the cartridge case headspaces on the shoulder of the case with "zero" head gap clearance.

A brass cartridge case has elastic stretch limits and when fired it springs back without deforming when within its headspace limit settings. Any rifle that is .002 to .003 over GO or minimum headspace is nothing to complain about. Remember a new cartridge case can be over .009 smaller than minimum headspace and proper fire forming is still the key to accuracy.

Below the "zero" GO reference mark when measuring your case.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5157.jpg

Below the average size of a new unfired case, which ran from -.001 to -.009, this case is -.006 smaller than GO or minimum headspace.

http://i122.photobucket.com/albums/o254/bigedp51/IMGP7214.jpg

Fired cartridge case with "spring back" + .001 over Go, my Stevens 200 has the headspace set +.002 over GO

http://i122.photobucket.com/albums/o254/bigedp51/IMGP5155.jpg
A brass

[airaddict]

I recently just set headspace on my first barrel. Its a 308. I just screwed the barrel down on the go-gauge (making sure it was fully seated in the bolt head) and snugged down the barrel nut. i tried out a new case and it chambered no problem. i then tried out a full length sized case and it was snug. I then tried a dummy round i had made for my feed length on my old factory barrel, it had used full length sized brass and bullet w no primer and it was a very snug fit.

So to test the tape on the end of the go-gauge, the bolt would not come close to closing, maybe half way thru its stroke. I measured the packing tape i used and it measured .003 by my calipers.

So can i assume min headspace is better for brass life? My bolt closes w a very very slight rub on the go-gauge. I should have gotten a no-go but i figured ide try the tape method first.

brian