Headspace...

So I finally got my headspace gauges in today. The rifle closed on the go gauge as it should. I then tried the no go and it also closed. But it didn't close on the field gauge. Obviously I need to have my headspace reset. But I'm getting ready to deploy for 9 months and would like to be able to get it out a lol bit before I do. Am I really safe to put 20 or 40 rounds through the rifle with it closing on the no go gauge so long as it didn't close on the field gauge, or should I just wait till I get home and get the headspace reset before shooting it?

I think you're worrying about nothing. I think you'll be fine. I wouldn't even worry about the headspace if it didn't take the field gauge. Your brass might not last as long...

Go shows minimum head space, No Go shows go +.005, Field shows minimum +.010 . If it closes on the first 2 but not on the field you have nothing to worry about as far as headspace.

You are fine. Fire away.

There are a few makers of headspace gauges that are making them to saami specs (the spec they made up) but not to .303Brit specs.

The GO gauge is .064", I believe, for all makers I have seen or heard of.
Forster gauges are .064 GO. .067 NO GO and .070 Field.
Milspec is .064 GO, .068 NO GO and .074 Field.

The middle gauge only exists in the factory. It is the spec for setting the bolt head in new rifles after proof firing. Every rifle that has been issued is tested by the .074" Field gauge and passed for service until it fails the .074" gauge.

Check the brand and size of the gauges you are using. Regardless of what they are, passing the field gauge means your rifle likely has many thousands of rounds left in it as is. Even more if they are the false Forster gauges.

Good luck on the deployment, maybe you can drop us a line here and maybe a few pics during...to stay in touch...

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Originally Posted by Son

There are a few makers of headspace gauges that are making them to saami specs (the spec they made up) but not to .303Brit specs.

The GO gauge is .064", I believe, for all makers I have seen or heard of.
Forster gauges are .064 GO. .067 NO GO and .070 Field.
Milspec is .064 GO, .068 NO GO and .074 Field.

The middle gauge only exists in the factory. It is the spec for setting the bolt head in new rifles after proof firing. Every rifle that has been issued is tested by the .074" Field gauge and passed for service until it fails the .074" gauge.

Check the brand and size of the gauges you are using. Regardless of what they are, passing the field gauge means your rifle likely has many thousands of rounds left in it as is. Even more if they are the false Forster gauges.

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That's interesting and good to know... I purchased the Okie gauges and the measure .060 for the Go gauge, .063 for the No Go, and .069 for the field gauge.

I just can't understand for the life of me why the question of Lee Enfield rifle headspace comes up time and time again, month after month, with monotonous regularity........... And every time it does, every Armourer here sits exasperated............ It is .064" GO and .074" NO-GO. Those are the measurements given by the developers, the designers and the manufacturers of the rifles plus the developers, designers and manufacturers of the ammunition. It is recorded FACT and has been for 100 years now. How difficult can it be? Anything else from Oakie or Forster or Uncle Tom Cobbley, Ford, MG or VW et-al is wrong or just a sales ploy to get you to buy their super-dooper 'false' gauges.

Here's a challenge.......... Does anyone disagree with that?

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Originally Posted by Peter Laidler

I just can't understand for the life of me why the question of Lee Enfield rifle headspace comes up time and time again, month after month, with monotonous regularity........... And every time it does, every Armourer here sits exasperated............ It is .064" GO and .074" NO-GO. Those are the measurements given by the developers, the designers and the manufacturers of the rifles plus the developers, designers and manufacturers of the ammunition. It is recorded FACT and has been for 100 years now. How difficult can it be? Anything else from Oakie or Forster or Uncle Tom Cobbley, Ford, MG or VW et-al is wrong or just a sales ploy to get you to buy their super-dooper 'false' gauges.

Here's a challenge.......... Does anyone disagree with that?

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I apologize... I'll refrain from asking questions or attempting to expand my knowledge about areas I'm lacking in from now on.

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Originally Posted by amadeus76

I'll refrain

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That's not what he meant troop...that wasn't for you.

Member "Parashooter" published a good article in the Technical Articles for Milsurp Collectors and Re-loaders(click here)

Headspace 101 for .303's (click here)

Also, you might want to try our Google CSE custom search engine located in the top right corner of the web site titled Search Milsurps.Com. It only searches our site using Google techniques and can be quite fast and more efficient then what other gun sites on the Internet utilize. For example, in your case, type in the words enfield headspace and see what happens. There are over 10 pages with dozens of old threads with many with pictures that you might enjoy, covering various aspects of this topic.

Hope that helps .. ;)

Regards,
Doug

It does get aggravating. Beware the coin gauges too. I've had several rifles sent here for "correction" after being checked with Okie gauges and found that they were perfectly fine using real MoD specification gauges. I'm not sure if it's the way folks install them or what but either way, I don't trust them and don't own them. No offense to American shooters but for some reason many seem to think that over headspacing the rimmed and very forgiving .303 British round will increase accuracy. This may well be the case when shooting rimless, higher pressure calibers like .30-06 or 7.62 Nato but it simply isn't true with the Lee Enfield. The chambers were designed with reliable function under all combat conditions in mind, not target shooters and reloaders. That little ring just up from the base of your fired brass is probably from a chamber that's slightly oversize but not out of HS specification. The reason the supply of long bolt heads has virtually run dry, is because so many have upgraded headspace in rifles that were perfectly fine to start with making it hard for guys like me to repair the rifles that really need them.

Just as Enfield had to put a stick in the sand and develop their own inch standard, there was an information void in that north american ammunition manufacturers were at a loss as to the standard 303 British chamber. The dimensions were all over the place.
But north american ammunition manufacturers had to be able to make ammo that would fit north american rifle makers' product.

So the Sporting Arms & Ammunition Manufacturers Institute (SAAMI) stuck thier stick in the sand and settled on their own set of standard chamber dimensions. Along with this came their SAAMI spec headspace guages.
Not a problem if one keeps everything as intended. Modern sporting rifles made to SAAMI specs take SAAMI spec ammunition and they are snug in the chamber helping reloaders. Chamber reamers are available to chamber or rechamber barrels.

Now everything is real cool and groovey shooting SAAMI ammo in a SAAMI chambered gun. Check the nice tight head space with SAAMI gauges and you are good to go.
But when a north american gun owner buys a set of headspace gauges from the local gun store shelf to check his ex military Lee Enfield in all probability, they will be SAAMI. Stores here tend to stock products for current mechandise, and not for obscolete Brit rifles that are no longer made. One has to really hunt around to find mil spec gauges. I had mine made for me.

Big problem, or what appears to be one when a mil spec rifle is checked with SAAMI head space gauges. It is possible for a mil spec rifle to pass the mil spec field guage, yet fail on the SAAMI field guage.

Vici verci, you shouldn't use mil spec head space gauges on a modern commercial sporting rifle made in north america that is chambered in 303 Brit. (eg. Ruger).

Confusion happens with the two standards.

So if your mil spec rifle fails the SAAMI field guage, no panic, check it with a milspec field guage, it might be just fine and pass.

"Vici verci"? On this topic, as they say, (in a Marlene Dietrich accent), in show-biz, "I'll show you where the "Vice is Versa"".

Headspace is important for assessing the potential "state of play" regarding striker "reach" and the possibility of primers backing out.

BUT, the latter is not a big problem when the "approved" ammo has its primers firmly held in via a heavy annular crimp.

As long as the striker has enough "reach" and power behind it, things will work. How many folk obsessively gauge their striker protrusion AND striker spring pressure?

As for "case life": in the "real world" of "authorized" ammo supplied, via tax-payer Dollars, Lira, Roubles, etc., the stuff is generally on a one-way trip after issue to the GI, Digger, Ivan, etc.

All through its production and even in storage, ammo itself is subject to its own rigorous regime of testing and gauging.

On the "two-way" rifle range, NOBODY is likely to be ferreting around trying to recover their brass during a "hot" contact or "fire and movement" operation.

For the rest of us, a "sloppy" chamber will radically shorten case life, as the brass is blown outwards to fit said "dubious" dimensions, and squeezed back via reloading dies. Millions of Arisakas operated just fine with "out-of-spec" chambers. They were "in-spec" just where they needed to be for reliable ignition and extraction, ONCE per cartridge.

As for actual specs; a quick comparison of "SAAMI" and "original" .303 chamber drawings reveals remarkable similarities. What happened in the "real world" was another thing altogether, ESPECIALLY after the rifles left the tender care of PROPER Armourers and Ordnance techs.

What a great thread. And I totally agree with the head space obsession.
The first thing I was told when I bought an Enfield was "better check the headspace!".
I was also told that I wouldn't have to dedicate brass to each rifle if the headspace was correct.

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Originally Posted by ricohman

I was also told that I wouldn't have to dedicate brass to each rifle if the headspace was correct.

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Sounds like you have found out that such is not the case!

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Originally Posted by Maxwell Smart

Sounds like you have found out that such is not the case!

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No kidding!
Each of my rifles has its own bag of brass.

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Originally Posted by ricohman

No kidding!
Each of my rifles has its own bag of brass.

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Pretty much the same for me too. I've got a couple that will use each other's brass quite happily, but no way for the rest.

They might headspace the same on the rim, but at the other end of the chamber they often are all different shapes

I had a fitter & turner machine me up 3 gauges I gave him a Mk VII round so he could mimic the unfired body taper they are within 1/2 - 1/1000th of an inch .064.5, .067.5 & .073.5 dont ask why I had the .067 made just read it somewhere I never use it anyway. I made him give me the round back all done for the universal Australian payment of a slab of beer.......

I only ever take issue with Englishman CA (thread 13) with my tongue gripped cautiously between my teeth....... But...... I dispute that the spec for .303" ammo chamber spec/dimensions are all over the place. The actual chambers might vary due to wartime needs etc etc or just plain fair wear and tear but the spec is well recorded in fact. And additionally, in reality, what goes on inside the chamber is almost academic in this respect BECAUSE THE CHS IS MEASURED OUTSIDE - FROM THE REAR OF THE BARREL TO THE FACE OF THE LOCKED BOLT. Nothing else matters.

As for different cases for different weapons, sorry, but it's just mind boggling!

Ah! But you're now talking to civvies Peter! I don't s'pose that the MoD have been forced to get the troops to neck resize their own brass..............yet.

I always feel bemused as well, at how the head space issue has become complicated over the years. I stick to the original British military specifications when headspacing rifles prior to proof. Specifically; the bolt should close over the .064 GO gauge, & not close over the .074 NO GO gauge.

To quote a Slavik furry rodent in a well known UK TV ad.........'Seeemples!'

For original barrels ive had no problem getting rifles through proof using the .064 GO gauge & the .074 NO GO gauge.

London Proof House are now using CIP spec for newly manufactured barrels ie Lothar & Criterion, which I've had to have a CIP No Go gauge manufactured recently which is the Go Gauge +0.004"

Yes, Brum Proof House is too, but I only submit original manufacture barrels on the rifles I take in, although my little stash is slowly running out. I may have to buy new barrels soon.......

But the general point I was trying to make was KISS - keep it simple. If your rifle headspaces between .064 & .074 it's ok to shoot (well, at least it is from a headspace point of view).

Clearly CIP know more about it all than Enfield do. But the problem Simon is that it's not CIP, Europe or the UK that seem to start the whole CHS palava going time after time. It all emanates from the US with these myriad gauge makers and specs and..........

My friends P'17 rifle was rejected on CHS at proof so I loaned him a set of just re-calibrated CHS gauges, complete with calibration certificate. They showed that the rifle was perfect. But not for the proof house......... Nope, I don't understand it either!

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Originally Posted by Peter Laidler

I loaned him a set of just re-calibrated CHS gauges, complete with calibration certificate.

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Some people don't treat their gauges like the instrument they are, like they're gold. When they take a bash or abuse, they don't read correctly. Some don't know that. After all, "They're hardened, aren't they?" (They'll ask)

They're hardened allright! How right you are BAR!!!!! Just eject them onto the concrete floor and see how hard they are when they hit the floor and crack. Or when someone snaps the rim off by slamming the breech block or bolt over it without removing the extractor........

Strange as it seems but, I'm told .22 now is an issue at proof.....

Peter or others if I insert either the .064 or .074 gauge through the mag well up under the extractor as I close the bolt with the extractor in place then carefully eject the gauge I.E stopping the extractor flinging the gauge onto the deck by doing this as the gauge is being withdrawn I place my palm under the mag well and one finger on the gauge as it moves to the rear is that ok to run the check that way. Or does the extractor have to be removed from the bolt head regardless. TIA

a stoopit question

CIP is the European equivilent of our SAAMI standard?

several forums suggest the CIP standard is to a tighter tolerance than our SAAMI standard? Is this so?

I'm looking to buy a chamber reamer. which standard would be the "better" specification/standard

What does CIP stand for anyway?

C. I. P.

Here.

See also:

thanks!

very interesting

my stupid question ~ if you are going to go to tighter spec's on the chamber are you getting custom made dies to suit like Neck and FLS as I am sure that the manufacturers would all work to the standard form or possibly the SAAMI spec either way would be interesting to know what the die people do as I use a Lee FLS.
I think Tbonesmith got a swag of the new Armalon barrels be interesting to know what reamer they used.........!

Chaps........., listen.......... with a .303" rimmed round it's NOT the chamber that counts, it's the length of the barrel in relation to the face of the bolt head. It is THAT distance that measures CHS. NOTHING to do with the bloody chamber

Pulling teeth or what.......................

You could strap a large field dressing to your forehead Pete.:)

Phew............ run out of them Muffer - I need a pillow! The thing that's keeping me sane at the moment is doing the zillion small jobs on my Mini Cooper that I've been meaning to do for the last 10 years. While I'm here, has anyone got a hydrolastic suspension type mini sitting waiting for scrap? But it's a nice sunny day here in Oxfordshire so it's outside.......

I thought CHS was measured from the base of the cartridge to the end of the neck oh well there you go. I have about half a dozen WWII 1st field dressings here and a few large shell dressings if you want one Peter........

Most? RIMLESS, bottle-necked cartridges have their "headspace" defined as the distance from the "base" to a specified diameter on the shoulder.

A notable, recent exception is the .357SiG. This BOTTLENECKED cartridge uses the end of the neck, as per MOST of the straight-walled (9mm Para, .45ACP, etc. Too much "yodelling syrup" for the Alpine boffins one day?

The term, "headspace" was first in use when there were NO "rimless" cartridges around. It just stuck. It's just a short-hand term for what can be a complex subject, requiring expensive metrology, especially gauges.

Anyone know how, or even IF it applied to pin-fire rounds and chambers?

I used to have a Mini, but a wheel fell off.

Peter, put yer helmet on!

Different specs from different standards.

When I went to school, we learnt cursive writing and printing. Now my hand writing is all flcked up as I use a combination of both, cursive printing. Then we changed over our monetary system to decimal. sixpence is worth 2-1/2 P. WFT??? Then we learnt the metric system. Feet, inches, pounds, stone, hundred weight, long ton, short ton, was now cm, kg.

I started a career as a draughtsman. My drawings had to contain nominal fractional inch dimensions in decimal (1/16" = 0.0625") with metric equivalent written below in mm.

Now I am in Canada, it is metric with next door neighbour using Imperial, or rather their own standard of it. 1 US gallon aint 1 Imperial gallon.

So having a set of standards for North America is business as usual for me. Makes sense that north american ammunition is made to north american standards to fit north american manufactured firearms.
It is not just by chance that you can take a shiney new SAAMI spec Winchester made round of 303 and fire it in your old SMLE (and then complain about case life).

Just curious, but to what standard do British firearm manufacturers use these modern times? Is it the old milspec? Does a modern British manufactured sporting arm still need chambers that will accept any manufacturer's ammo in battlefield conditions covered in mud or sand?

I guess what I am trying to suggest is that the world goes around and has moved on. There are still some folks buying commercially loaded 303 Brit ammo and there is also a small demand for new sporting arms chambered in such. The new specs (SAAMI, CIP) are for these sporting arms, they were never intended for use with surplus battle rifles.

If I did work on modern sporting arms, I would have a set of modern gauges.

I understand that chamber dimensions do not have an effect of head space and that they are two separate issues with their own individual gauging. However, they are related and connected in this conversation by the same named set of standards.

Not rocket surgery, mil spec gauges for milspec arms, SAAMI spec gauges for SAAMI arms and CIP gauges for CIP arms.

Mix them up and it becomes FUBAR'ed.

Pondering further; how many folk have used and maybe still have, "rim-thickness" gauges for .303 ammo.

Back in "the day", no "well-equipped" full-bore shooter would be without one of these.

The idea, and it has SOME merit, is that different rim thicknesses, coupled with "correct" headspace, could produce ignition variations, and thus, different points of impact.

Hard-core competition RIMFIRE types STILL have their own versions of this gauge. These are used to select cartridges having a "rim" thickness" in a fairly narrow range, to reduce variations in the ignition of the priming compound contained within that rim.

It's mostly about thinning the herd of variables, not to mention a bit of "Zen" or, "The Force" or what have you. "Fashion statements" also have a role to play; see; "gadget gamesmanship".

A "THIN" rim will allow the round to "float' a bit, possibly lessening the depth and "speed" of the striker fall, and thus, minutely alter primer performance. Hard-core bench-rest types batch their brass, and gauge the seating depth of their "special" primers, after "uniforming" the pockets and the flash-holes.

Have a close look at the operation of the extractor on a Lee-Enfield: It actually holds the case fairly close to the bolt-face whilst in operation. Going back to J. M. Browning's 1911, the "as designed" chamber had NO distinct "step" where the case mouth could engage, just a taper (leade). The "floating" striker CAN protrude a LONG way forward, but it is not exactly propelled by a Mauser or Lee-Enfield grade striker spring. The extractor is expected to stop the relatively low pressure .45ACP case from "getting away". Browning hedged his bets with the .38 Auto / .38 Super, giving it a minuscule "semi" rim that is supposed to engage a "cutout" in the barrel hood. Not much point, as it turned out. Guns in the slightly shorter and MARGINALLY tapered 9mm para work just fine as well, without much of a chamber mouth "step".

Open-bolt SMGs are a different bucket of bait.

Funny enough, some other guy at the range Saturday, while I was shooting with my SMLE, addressed the matter of headspace, asking me which measure of bolt-head I was using.
Seems to be somewhat an argument to sound as experts.......
Good luck on your deployment Amadeus!

You will find a lot of experts at the range, there is a lot of good and bad information on the internet. I enjoy chatting with them, but some come out with some remarkable comments.

I have heard some interesting tidbits and some gems over the years.

This is really interesting, thank you.

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Originally Posted by englishman_ca

I have heard some interesting tidbits and some gems over the years.

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Interesting way to put it...

Well at least I learned a few things from this thread but for those of you in the world of firearms and weapons think you are hounded by those that cannot think well this from my world of operating cranes for nearly 18 years I learned allot.
Some things that have entered my world from the universe of DADS (Dumb As Dog Sh*t)
If I had a $1 for every time I have been asked by a noob "Have ya tipped one over yet mate." I would be fliking rich and no I haven't but have had a few scares with ground liquification and unknown soak wells put there 30+ years ago!.
"But it is a 160 tonne crane why can't it lift it" "Well its 160 tonne at 3 meters with basic boom and 50 tonne of counterweights" not 30 bl**dy meters away."
"Look here you can drive up my concrete driveway it will be ok its 75mm thick." "Sir, the crane weighs 60 tonnes without counterweights best you get some sand for the trenches my tyres are going to leave in your front lawn." usually 900mm wide by anything up to and beyond 300mm deep.
"There is plenty of room you will fit through the gate its 3.5m wide." " Well Sir I do not think so I am 3.9 meters wide with the mirrors folded in and 16 meters long!"
Then you have the classic a 60 tonne vehicle doing 60kph and a car pulls out 20 meters in front of you its an automatic crane there is another car beside you in the camera (Left hand drive crane) you only have the telmar and the brakes if thats not bad enough a young child gets up and looks up over the rear sill.

Once I pulled out of an irrigation drain a van which had aquaplaned off the road and the young child (4 years old) was missing the police stopped me and commandeered me and the crane I slung the vehicle as no one there had a clue and winched that van upside down out of the full drain I half expected the little tyke to fall out of it, but he didn't his body was found 2 klm's down the channel.

We all in our lives or trade have horror stories good and bad, but one thing I did when training people on cranes because a crane can kill and maim just as well as an artillery round or a bullet with my students I had under my wing in my mantra there was "Never a dumb question just a dumb answer..........."

Next time you see a large crane say with 60 meters of boom out roughly 180-185 feet then if your within a 60m radius of that crane then your in the death zone if it goes pear shaped and falls your way, also if he has his headache ball with 20 meters of rope out under the boom tip then if it tips sideways then that can be flung further out like a lead ball on a string............
That is @1 millionth of the stuff I learned or had to contend with whilst operating a variety of hire crane across this state Western Australia look it up and you will get the drift how vast our state is, at least at 80kph top speed you got to see the scenery.
Last one, we were issued with salt to throw out the windows to keep the snails back whilst going up hills they caused you to lose traction........Cheers.:cheers:

The new Criterion barrels are chambered to SAAMI specification and come with short chambers and long shoulders so they can be turned for proper "crush" and headspaced to a "0" bolthead using a finish reamer.

Well done, Criterion.

They took the "risk" AND put in a LOT of thought and research.

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Originally Posted by Bruce_in_Oz

Have a close look at the operation of the extractor on a Lee-Enfield: It actually holds the case fairly close to the bolt-face whilst in operation..

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The extractor claw is disengaged from the rim when the bolt closes. With the aspect of the claw to its pivot, as it comes away to the side it would also be opening the gap back to the bolt face.
I did some pics with a dial indicator on my skeleton action a while back.... I'll see if they show how much.

"The extractor claw is disengaged from the rim when the bolt closes."

Good point. You can see the extractor start to pivot outwards as the bolt-handle is locked down. But, as near as I can make out, it never deflects far enough to be completely clear of the outer diameter of the rim. Again, this ties in with the whole beauty of the helical locking system on these rifles.

As the bolt handle is raised, because the bolt-head thread is a coarse right-hand thread, the bolt head only moves back a little, initially, until the "little" lug on the bolt body picks up the 1: 1inch unlocking cam surface and starts the primary extraction process properly.

Clever things, these old rifles.

I think it shows pure genius of the designers of the rifle between the 2 rifles the MkIII and the No.4 did they alter the lock up at all on the system or left well enough alone and designed the receiver for the No.4 around that principle

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Originally Posted by Bruce_in_Oz

"The extractor claw is disengaged from the rim when the bolt closes."

Good point. You can see the extractor start to pivot outwards as the bolt-handle is locked down. But, as near as I can make out, it never deflects far enough to be completely clear of the outer diameter of the rim. Again, this ties in with the whole beauty of the helical locking system on these rifles.

As the bolt handle is raised, because the bolt-head thread is a coarse right-hand thread, the bolt head only moves back a little, initially, until the "little" lug on the bolt body picks up the 1: 1inch unlocking cam surface and starts the primary extraction process properly.

Clever things, these old rifles.

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Couldn't agree more. The design features that made this action so good and saw it through such a long service life are taken for granted by so many- because they just work so good.

I did a few pics a while back demonstrating primary extraction too. The bolt head is screwing forward as the handle is lifted, but the camming action of the lugs while unlocking still brings the bolt face back enough to break the grip of the chamber on the case. The mechanical advantage is huge! Over two inches of travel on the bolt knob giving so little rearward movement of the extractor.
I had to try to explain why a case should not be still stuck in the chamber once the bolt handle was lifted. Sometimes it takes a lot of work to change the things people have set in their heads...

I'll stick all the pics up shortly.

Ok.. back to my earlier post, here are three pics, first showing the dial indicator on the extractor claw, the bolt almost closed just at the point where the curved surface to the inside of the claw meets the curve bottomed angled recess in the back of the barrel.
Second pic shows the bolt closed and the claw has come away from the base pf the cartridge by almost .1 mm.
Third pic is of the back of the barrel where the recess for the extractor is and the bolt just starting to be withdrawn, viewed the side through the cut out in the receiver ring.

Attachment 84272

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Attachment 84273

Next up, pic one shows the bolt closed. Dial indicator on the back of the bolt head.
Second pic has the bolt handle just lifted a bit and the dial indicator is reading .11 mm. Only a very small movement for the inch or so of lift on the bolt handle. This is where the mechanical advantage makes it so easy to break the grip of the case from the chamber.
Pic three shows the bolt up completely unlocked and ready to be drawn rearward to complete extraction and eject the spent case. Note, there has been no more rearward movement of the bolt head from the previous pic meaning that primary extraction should take place in the first half of bolt lift.

Attachment 84275

Attachment 84276

Attachment 84277