Lets Talk Headspace...

[Kansas Ed]

OK, now what I'm after is the effects of excessive headspace from a measurable standpoint. I know that headspace is supposed to be a bad thing, but to what extent is it an issue. I know all the fixes, and I've heard all the wives tales. But except for go / no-go gauges telling a "smith" that headspace is excessive there isn't that much out there to indicate that this is based on anything other than the gauge makers judgement, or the "smiths" personal bias as to what "excessive" is. And no one I've ever talked to has indicated that they have an inkling of when it becomes a problem. Get what I'm after here?

So say we take the basic 30-30 for sake of ease. And we give it increasing amounts of headspace. There is supposedly a point where brass life takes a major hit...say being reloadable from 12 times to 4 times. And then there is the rumor that headspace is hard on firearms...at what point is it hard on firearms? +.005, .008, .012...etc.

Has anyone ever looked at this? Is there some proven results which measure brass life, or results which truly indicate a measurable life expectancy decrease in the life of the firearm?

And (I know Ackley's answer to this question) assuming the primer is backing out, does that indicate that the only ill effects of excessive headspace are relayed to the brass, as the bolt face obviously isn't getting any pressure?

Ed

[AJMD429]

I've always wondered how cases which headspace on the rim can really have any serious issues with excess headspace (within reason), since all that I'd think would happen is the brass would slide back a few thousandth's, and it would have to be pretty far back for the unsupported area just in front of the rim to give way, wouldn't it..? Not that I'm planning on trying it...

[NonPCnraRN]

A few thoughts. In the case of the 30-30 Imp, if you fire regular 30-30 ammo you get a fireformed case. In fact it expands to the chamber size which is what you want it to do in the first place. It is only when you took that fireformed 30-30 Imp case and resized it to its original 30-30 shape that you would run into trouble. If you had dies reamed to match fired cases of a gun that had excessive headspace then wouldn't the result be the same? You would have brass that was specific to that gun. With a levergun firing straight wall pistol cartridges it would be the same as firing 44 spl in a 44 mag chamber or 38 spl in a 357 mag case which is done all the time. Now if the chamber was oversized in diameter then you would have either split cases or a lot of blowback. Also the bullet would lie toward the bottom of the chamber and not start down the barrel centered in the bore.

[Kansas Ed]

This is what I get into when I can't talk with my hands I get misunderstood more easily than normal

What I am getting at is.....for example:

Has anyone done any tests on standard cartridges...say 30-06, 30-30, 308, 223 et al...where they determined that brass life was say cut to 50% when the headspace dimensions were .00X" vs when they were .00Y".

Or say Model XYZ rifle started to exhibit cracks on the locking lugs after X amount of rounds when the headspace was greater than .00Z"

What I'm after here is proof that the term "excessive headspace" isn't just some subjective number dreamed up by someone wanting to drum up extra business in his gunsmith shop. And then that becomes some urban myth that a "no go gauge" must be .006" greater than the "go gauge" or "the gun will self destruct the first time you fire it and kill all of your extended family" type of thing.

I suspect that the cartridge design comes into play also, so that's why I'm asking for standard cartridges. Because I'm sure that +.010 headspace has less effect on the 38-55 than it does on the 25-35 due to body taper issues. Likewise I'm sure that cartridges with less pressure are less affected than others with similar designs running at higher pressures, though the argument could be made that less pressure could equate to more bolt thrust due to less adhesion to the chamber wall. So there are a lot of caveats there.

I have read that the headspace gauges are quite different between the .308 and the 7.62 Nato, though it's just standard practice for people to run the 7.62 through their .308 rifles without incident, which results in quite a bit of more headspace IIRC.

Ed

[Kansas Ed]

I've always wondered how cases which headspace on the rim can really have any serious issues with excess headspace (within reason), since all that I'd think would happen is the brass would slide back a few thousandth's, and it would have to be pretty far back for the unsupported area just in front of the rim to give way, wouldn't it..? Not that I'm planning on trying it...

See, this brings up another point. I shoot some pretty old stuff, and the headspace on some is probably questionable by modern standards. How do I know? Well, I see on some of my firearms primers backing out a little. But this indicates to me that the bolt face/receiver isn't seeing any pressure or thrust because if the primer is backing out that indicates that the brass is adhering to the chamber walls and not beating the bolt. So if I'm reading this correctly...the brass is likely getting some extra stretch which will cut down on the amount of times it can be reloaded due to case head separation issues. But there is no undue strain on the firearm itself...if I'm reading this right. But if we should oil the chamber or other manner of making the brass "slip" then all bets are off.

Ed

PS: CATIA has been kicking my butt for about 12 hours now...I need the distraction

[Cliff]

I believe that Phil Sharpe in his book, "The Complete Guide to Handloading" did a very good section on headspacing. He did extensive testing concerning headspacing and it does explain a lot. He worked primarily with the 30-06 cartridge and had acess to a Browning machinegun which had a screw in adjustable barrel. He found he could go to .125 excessive headspace. He said most problems complained about excessive head space came out after sporters made from military rifles started hitting the market. The makers didn't know or couldn't know their makes true head space so it sounded good to point to excessive head space for a bunch of problems. Also Julian Hatcher's Notebooks dealt in good detail for headspace. He was the go-to-guy at Springfield Arsenal when a report of weapons failing was reported. Good reading in both if you can get your hands on them. In the days these were written 50K was considered the High End pressure, compared to most small arms which used 40Kpsi as top end presssures. Seems the quaility of brass used in the cartridge cases could be iffy a whole lot more than good brass is today. Maybe you get a copy someplace and read it over. Good Luck.

[Hobie]

The biggest problem I see with excessive headspace is poor ignition/insufficient strike on the primer. Most of my experience in this regard has been with various cartridges chambered in the Thompson Center Contender tip up system. Comments apply equally to the Encore or G-2 guns.

We had a fellow come in with a .25-06 Encore barrel which had been re-chambered to the .25 STW. The guy who did the work apparently ran the chambering reamer in a bit more than he should and compared to the other guns the smith had done this one guy was having problems even getting his ammo to go off much less be accurate. He was getting flattened primers with mild loads because the primers would back out and then the case would come back and push the case against the breech face. It also shortened case life because he was setting the shoulder back when he resized. All he needed to do was to partial full-length resize or neck size the cases. In fireforming cases he needed to use a mild load with the lighter bullets seated out to actually seat in the leade/throat to push the case back against the breech. Apparently all his problems have gone away. He was in the shop saying his barrel shot like the others and the .25 STW was a barn burner! He is now pleased with his barrel.

This doesn't mean I'm a genius. As Contender shooters know this is necessary for best results even when shooting RIMMED cartridges like the .30-30 and its derivatives.

[Old Time Hunter]

Not to throw a wrench in the deal, but take a look at the Springfield Trapdoor. It was made to have what we commonly call excessive head space. If it did not, how would you close the breech block? Maybe that is why they had "balloon" cartridges?

[Thunder50]

For what its worth, I would think the problems with "excessive headspace" is the failure of the cartridge case near the base of the cartridge. I am sure many cartridges would work fine the first time, but if there is no support to the brass, after resizing an X amount of times, since brass work hardens, it might not withstand the pressure and rupture. Now, if you had a grossly excessive headspace, you might rupture the case on the first firing. I would also think the cases would "grip" at the front of the chamber first (thinnest brass) and the case would grow rearward upon firing, thus setting up a case for casehead failure later. 50BMG shooters have this problem with brass fired in the "ma deuce" and headspace is not correctly set. You have a case that is thinner at the web and sometimes it will crack after only one or two more firings.

The main problem would also be that if you full length resized to factory dimensions, then pretty soon you would have case head seperation. If you set your dies to where, on bottleneck cases, you only size to the base of the neck, I don't think you would have a greatly reduced case life, but I would suspect that you might lose a few loadings.

Look at NEF and their 35 Whelen barrels. I understand some were chambered too deep and people were having trouble getting them to fire. Some would seat a bullet to where it was touching the rifling, so when fired, the case would conform to the chamber, then setting their dies to their fireformed brass and things were fine.

At what point it would rupture on first firing, or exactly case life would be, I cannot say. I am sure things would be different for a 40K psi cartridge vs. a 50K psi cartridge vs. a 55K psi cartridgle, along with the variable of case diameter thrown in. Would be interesting to know, but I don't really want to donate any rifles to the cause.

[Charles]

My thoughts on the subject at hand:

1. a long chamber (excessive headspace) becomes a problem when a cartridge fired in it, stretches beyond the tensil strength of the brass and ruptures letting loose all of that nasty gas to find it's way out.

2. Most often on a rimless case, this can be compensated by neck sizing the once fired brass, providing the brass has not stretched dangerously thin already on the first firing.

3. Then there is a problem of the possibility of poor ignition because the case is too far forward in the chamber and the firing pin doesn't give a positive strike. This happens when a round with orginary headspace is fired in a chamber that is too long.

4. A rimed case does indeed headspace on the rim, but that won't prevent the case from stretching beyond it's tensil strength is the chamber is too long and the shoulder is too far forward. The brass will stretch until stoped by the chamber shoulder.

5. Repeated full length sizing of rimed cases in a long chamber will in a few loads cause the case to separate. The British SMLE in 303 is famous for this.

6. The best way to tell if your headspace is funky is to buy a Wilson case gage at the cost of about $12.00. Size the neck of your case, but don't touch the shoulder and drop the case in the gage. There are steps on the case head length that will give you max and minimum headspace of the fired case which mirrors your chamber. It also will give you the max and minimum case length on the other end. These gages also have several other uses. I have on for every caliber I load.

7. The original question is how do you know when headspace becomes a problem? If you chamber is too long and the case shows excessive headspace on the Wilson gage, section the case with a hacksaw and take a look at the wall thickness above the web. If it is thiner than the case wall above, you have a potential problem. If not, then neck size and go about your business.

8. If the case stretches far enough to thin the brass above the web in the first firing, it is time to do something about that long chamber. You are playing with fire if you don't, as the brass will continue to flow forward, even if you only neck size and one day....boom..here comes the gas.

9. Some really strange things can happen when you turn the gas loose. I got a serious split on the side of some Pre-war Remington Palma match ammo, when I fired it in my match 03. Some of the gas came back through the firing pin hole into the bolt with enough force to blow the cocking piece back to full cock. This is why folks wear shooting glasses and I had a good pair of Ray-Ban shooting glassed on. Even though it was 1961 we knew to wear shooting glasses even though they cost as much as a rifle. Don't fire a round without them!

[1894cfan]

Since you guys are talking about headspace type stuff, I've got a Win 94 that was made in 1977. When firing Win 150PP factory loads, some of the primers are backed enough to feel and others are flush with the case head. Do you think I might have a wee bit of a problem here? Just seems a little weird to me.

Also, just to give you a bit of history on the rifle, it was found in a partially burned crashed airplane and rebuilt.

[Buck Elliott]

Since you guys are talking about headspace type stuff, I've got a Win 94 that was made in 1977. When firing Win 150PP factory loads, some of the primers are backed enough to feel and others are flush with the case head. Do you think I might have a wee bit of a problem here? Just seems a little weird to me.

Also, just to give you a bit of history on the rifle, it was found in a partially burned crashed airplane and rebuilt.

Probably. No... definitely.

[Old Time Hunter]

So..are these cartridges indicative of a headspace problem or chamber problem?

[1894cfan]

Since you guys are talking about headspace type stuff, I've got a Win 94 that was made in 1977. When firing Win 150PP factory loads, some of the primers are backed enough to feel and others are flush with the case head. Do you think I might have a wee bit of a problem here? Just seems a little weird to me.

Also, just to give you a bit of history on the rifle, it was found in a partially burned crashed airplane and rebuilt.

Probably. No... definitely.

Buck, just to make sure I get this straight from you, you think I do have a headspace problem here? TIA

[Buck Elliott]

Yes.

[1894cfan]

Yes.

DANG!! What's the procedure to take care of that problem on a Win 94? I don't want to turn my Dad's 30/30 into a wall hanger.

[Charles]

1894fan... Maybe I should not stick my nose into this but......I am not so certain you have a problem. My first question would be...what is the load you are using. You didin't mention this. This could be very important because....

1. There is enough extra headspace is almost all rifles to allow the primers to move to the rear a tad. When the peak pressure is reached, the case head is slamed back against the breech reseating the primers flush with the case head.

2. If your loads are light, the primers won't reseat. This may be what is going on.

3. The fact that the primers are backing out a slight amount and others non-at-all leads me to believe you don't have much of a problem, if one at all.

4. Before you get your nickers in a twist, either check the headspace of your rifles with headspace gages, or your cases with a Wilson gage. If you don't want to split for a Wilson gage, then send me a couple of fired cases and I will check them for you. I also have 30-30 headspace gages, but I am reluctant to mail them out, because they are a little tricky to use.

5. The long and short of this is don't hit the red button yet. Even if you have a slight headspace problem, you can compensate by adjusting your reloading dies.

[1894cfan]

1894fan... Maybe I should not stick my nose into this but......I am not so certain you have a problem. My first question would be...what is the load you are using. You didin't mention this. This could be very important because....

1. There is enough extra headspace is almost all rifles to allow the primers to move to the rear a tad. When the peak pressure is reached, the case head is slamed back against the breech reseating the primers flush with the case head.

2. If your loads are light, the primers won't reseat. This may be what is going on.

3. The fact that the primers are backing out a slight amount and others non-at-all leads me to believe you don't have much of a problem, if one at all.

4. Before you get your nickers in a twist, either check the headspace of your rifles with headspace gages, or your cases with a Wilson gage. If you don't want to split for a Wilson gage, then send me a couple of fired cases and I will check them for you. I also have 30-30 headspace gages, but I am reluctant to mail them out, because they are a little tricky to use.

5. The long and short of this is don't hit the red button yet. Even if you have a slight headspace problem, you can compensate by adjusting your reloading dies.

Thanks for jumping in, Charles. I've been shooting two different loads in my 94, FACTORY Win 150 Power Point ammo and reloads of 9.0 grains of Trail Boss with Hornady 86gr JSP's. While the reloads do expand the cases, they don't back the primers out like the Factory ammo does, velocity is about 1400fps. PM your address to me and I'll send a few fired cases to you to check out.
Maybe I'd better back the sizing die out a bit and start playing around with it a bit more.
Thanks,
1894cfan

[mescalero1]

Do a chamber cast with cerro-safe
I will talk you through the measurement process
This IS the ONLY way to know what is going on inside your chamber!

[1894cfan]

Do a chamber cast with cerro-safe
I will talk you through the measurement process
This IS the ONLY way to know what is going on inside your chamber!

Where do I get this cerro-safe? TIA

[mescalero1]

I purchase it at my local ( gun ) toy store.
Try Brownells.

[1894cfan]

I purchase it at my local ( gun ) toy store.
Try Brownells.

Thanks. Now to make up ANOTHER order with them.

[765x53]

My headspace experience involves shotguns. The difference between minimum headspace and maximum headspace in identical guns is the difference between a shove and a roundhouse punch in felt recoil.