Head space

[possum1]

This headspace thing, I just couldn't grasp it in my mind " too small I'm sure ", PM'ed biged and he really explained it to me. The "way" some of us are headspacing is correct, the only draw-back is there is a good possibility the rifle's won't chamber Factory round's. Like froggy said I'm not planning on it.

[Got Diesel]

In my case I am setting up a 308 Win. I have a set of forster gauges for it. Run it down on the go gauge tighten the barrel nut up good and snug. Remove the go gauge and replace with the no-go gauge or try to. It won't close on the no-go gauge, gets right to where the bolt would begin to turn down and stops. The thing is the go gauge must be right on the minimum because when chambering a factory round it's a bit of a stiff bolt. Using a full length sized piece of brass the bolt closes great nice and smooth. So what I am getting at is even with using a go gauge the gun may still not like factory loaded ammo.

[WyrTwister]

I am considering changing the barrel on a Savage . The way I would do it is to install a Go in the chamber ( with the bolt closed ) and screw the barrel down snug , against the Go . With the bolt still closed and the Go still in the chamber , I would tighten the nut down .

I would then see if the barrel would close on a variety of factory ammo . If it was too tight , I have a .002" and .004" shim cut from an automotive feeler gauge .

I would sandwich then .002" shim between the bolt head and the Go and re-set the HS . Then check with factory ammo .

Word of caution , use very light pressure when atempting to close the bolt , as in pressure from your pinkey finger .

God bless
Wyr

[Cover Dog]

rjtfroggy..........."Then I put a piece of masking tape on one and that made it .003 longer"

I have NEVER used masking tape, I use frosted scotch tape. I measured some masking tape I have on hand and it measures .0055 thats more then 3 times thicker then the scotch tape.

Maybe someone will jump in here and give their opinion and what type of tape they use.

[Dirk]

Screw the tape. Use a NO-GO gage!

[Cover Dog]

I have always used both go/no go when headspacing. I also use the tape on the go gauge after I have headspaced to see just how much "space" is left. Usually one thickness is enough to make the bolt handle somewhat hard to close. And with two it won't move.

[AZ-K9]

For the newer builders out there I think the video from the Savage sight is valuable with regard to setting headspace and explaining the floating bolt concept.

For the impatient, the headspace setting is explained at about 2:30 to 4:30 in the video....

http://www.savagearms.com/accuracy

[51Bravo]

Is it necessary to remove the extractor before headspacing?

Wood

[Blue Avenger]

no, but a lot of guys like the extra warm feeling that it did not hinder the operation and remove it.

[AZ-K9]

Is it necessary to remove the extractor before headspacing?

Wood

No, but be SURE your headspace gauge is UNDER the extractor and not on top.

[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.

[img width=564 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0704.jpg[/img]

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0706.jpg[/img]

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0710.jpg[/img]

[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.





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

[img width=600 height=272]http://i122.photobucket.com/albums/o254/bigedp51/9-3.jpg[/img]

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

[img width=600 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP0727.jpg[/img]

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. ::)

[img width=337 height=450]http://i122.photobucket.com/albums/o254/bigedp51/IMGP7241.jpg[/img]

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



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.



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.

[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-...h-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.