Bad News, No. 4, Mk I

[mikld]

Well, I took the advise given me and purchased a coin type "field" headspace gauge. The bolt easily closes on the gauge :(. I open the bolt, cleaned the bolt face, wiped any excess oil from the gauge, place gauge on bolt face, gently close bolt. I guess I just got excited about a new shooter for my collection (I spent 4 days cleaning the action, stock, and barrel, and purchased a box or ammo, $32.00+, a gauge, and did some reading/research.). Oh well.

I only paid $79.00 for it back when and don't want to invest in another barrel or have the present barrel "set back". So, she goes back in the cabinet...

[budster]

Look at the bolt head.
There should be numbers of 0-3. Sometimes you can get another head with the next number up. This will tighten up the head space. Also, in years past, some gunsmiths have slightly peened the bolt (not the bolt head) around the area where the bolt head tightens up against the bolt moving metal toward the bolt head to take up the slack.

[M1Garandy]

What are the specs on the field gauge you purchased? Not all .303 British field gauges are created equal.

[George in NH]

Since I do not know, I will pose my comment as a question. What is the proper procedure to check headspace on this series of rifles? As in removing the extractor and/or the firing parts of the bolt?
George in NH

[Parashooter]

1. Remove extractor, spring, and screw from bolt head. (Optional, but saves novices from mistaking extractor spring resistance for gauge resistance.)
2. If gauge doesn't have a central hole to clear firing pin, make one.
3. Hold back trigger so mainspring doesn't compress during closing.
4. Open and close bolt several times, slowly, to observe and remember normal resistance with no gauge present.
5. With muzzle down, place gauge in/on chamber (coin-type gauges don't really go in the chamber).
6. Hold back trigger and attempt to close bolt, stopping when encountering any resistance greater than when gauge was absent.
7. If bolt rotation shows any incremental resistance before fully closed on a .074" gauge, headspace is acceptable for service use.

For more information, see http://parallaxscurioandrelicfirearmsforums.yuku.com/topic/3361/Headspace-101-for-30339s

[mikld]

Oakie headspace gauge measures .074". Bolt head markings are "S", flaming bomb, and number "2". Bolt head is loose in bolt, as in not screwed in tight (might go 1/4 turn more), and I guessed this is to allow bolt head to turn to remove bolt from receiver. Numbers on bolt handle match rifle's serial number.

[budster]

You need a #3 Bolt Head and it is supposed to be tightening up at about 15 deg BTC and not be sloppy...The .303 Brit Hd Spaces on the rim of the case.
IIRC, The S marked bolt head is the longest
See if https://www.gunpartscorp.com/ has a bolt head.
And...here is a thread to read to educate you http://parallaxscurioandrelicfirearmsforums.yuku.com/topic/3361#.Uovh9imA3IU

[Detroit-1]

just getting a number 3 bolthead might or might not help you! You have to measure the length of the bolthead you have and then get a longer one! Then it has to index right! I can't believe any gunsmith, who knows Enfields, would ever peen over a bolt to correct head space! That is just nuts! Oh and just becauce a bolthead is marked #3 does not make it always longer! A S marked bolthead is a Savage bolthead! Go to Gun Boards Forum under Enfields for the truth.

[SMOKEY]

Try Privi Partizan ammo for around $15 a box. Shoots real fine. If looking for parts try Liberty Tree Collectors. They have a fair selection. Most are fairly priced, some pricey too.

[JB White]

Another thing to keep in mind that 0.074 was determined to keep a combat rifle operating smoothly in the field. The HS might be a little loose but that doesn't mean the rifle will explode on firing. You just won't be able to safely reload the overstretched brass with confidence. During wartime, the emergency spec was .084 and they served well enough then.

Yet another thing.....HS increases over time while the rifle is being used. There is more to it than simply replacing a bolthead to tighten things up. The actual problem could still be lurking elsewhere while the new bolthead only masks the numbers. I have a NOS unused #3 bolthead in my spares box for "just in case". After at least 15+ years I still haven't found a case which would justify its use.
The numbered boltheads were originally devised as a labor saving device at the factory when the headspace was being set for the very first time. Cut down on the stoning it took a skilled craftsman to do when the work was being done by semi-skilled personell. Armorers who used the spare boltheads later did so with a plethoria of proper tools/gauges and a pool of experience at their disposal.

That having been said...I know of several instances where common 0 and 1 boltheads were installed prior to selling in order to glean a few more bucks later on the scarce #3 and later on, #2 boltheads which were already in the rifle. Not that I did it mind you! I never sold a rifle which didn't check out and that I hadn't used myself.

[Parashooter]

If you handload for a .303 with generous headspace, there's seldom a need to mess with bolt heads - changing the rifle's clearances to yield longer case life. You can control cartridge end-play simply by changing technique.

When you fire a new case for the first time, use an improvised spacer ahead of the rim - anything from a precision metal washer to dental floss can work to hold the the cartridge head firmly against the bolt face and eliminate or reduce stretch even if axial clearance is significant. Another way of accomplishing the same end is to use a bullet seated out far enough to jam into the lands, "headspacing" on the bullet instead of the case. Such techniques are useful only if the rifle has excess headspace. With normal headspace, initial stretch isn't enough to worry about.

http://i43.tinypic.com/e5s8es.jpg

After you've fire-formed your new cases they will fill the chamber fully, stopping on the shoulder just like a rimless cartridge. If you neck size, you'll have zero "headspace". If you have to full length size, adjust the die so the cases chamber with just a bit of resistance in the last few degrees of bolt rotation. Keep the pressures below maximum and you also reduce the small amount the bolt and receiver compress/stretch on firing in a rear-locking action.

With these techniques you can make your .303 cases last for dozens of loading cycles, even if your "gauge headspace" is well beyond the .074" field spec or even a bit past the .084" wartime expedient limit. (Of course the rest of the rifle has to be in sound condition.)

To demonstrate how we can control head clearance using only the shoulder, I filed off the rim of a once-fired Remington .303 case. After adding an extractor groove to fit a Mauser-size shellholder, I neck-sized, reloaded and fired this case 19 more times.

http://i40.tinypic.com/5foqqr.jpg

The load was a 180-grain jacketed soft-point over a lightly-compressed charge of IMR 4350 (giving an average velocity of 2310 fps for the 19 shots and listed at just under 39,000 CUP in my IMR data booklet). The test rifle was a 1943 Lithgow S.M.L.E. Mk.III*. 20 shots was enough for a practical test, I sectioned the case to examine the web/body junction area where thinning normally occurs.

http://i42.tinypic.com/vq4ej8.jpg
This case, fired 19 times with no rim, has not stretched or thinned at all. I'm sure it could have continued for at least another 20 of these moderate loads.

It's clear to me that the .303's shoulder, alone without help from the normal rim, is entirely adequate to maintain "headspace" when sized in a way that preserves the shoulder location. Those handloaders who experience poor case life with neck-sized handloads should look for other factors to explain premature case failures. The most likely source of trouble is high pressure. More pressure means more action flex and that means shorter case life.

[Alan De Enfield]

No4 / No5 Bolt Head Survey – Results, Conclusions & Suggestions


Background:
A few years ago, having always wanted a ‘bit of history’, I purchased a Savage No4 Mk1*, it turned out that this rifle had a No3 bolt head and whilst it ‘passed’ the headspace test I thought I’d better get a bigger bolt head for when I wore out the size 3, I started looking for a size 4 bolt head which are only available in the land of ‘unobtanium’ (In the last three years I have only ever heard of 3 examples).
During my quest I was informed by several ‘old hands’ that the bolt head size (number) was a guide only and in many respects was a meaningless number, “Cannot be right” – I thought, why put a number on it if its meaningless, and thus started my research into bolt head numbers / sizes.

I measured my (slender) supply of bolt heads and had a good response from members of another forum, which gave me a good basis for the evaluation, with the additional ‘numbers’ from members on Gunboards I feel the results give a good representation of the actual dimensions of bolt heads.

What Size Should The Bolt Heads Be ?

It seems to be generally accepted that No4 / No5 bolt heads should fall in the following range :
Size 0 = 0.620” – 0.625”
Size 1 = 0.625” – 0.630”
Size 2 = 0.630” – 0.635”
Size 3 = 0.635” – 0.640”

Whilst I don’t question that this information is printed somewhere, I have not been able to find the original source, the information I have found does not actually state the ‘starting’ dimension, only that the sizes are incrementally larger :

a) From “Parts Identification List Rifle No4 Mk1 and Mk1*” dated 1945
Bolt head 0 part number BB8584
Bolt head 1 part number BB8585
Bolt head 2 part number BB8586
Bolt head 3 part number BB8587

“Number 0 to 3 increase in length by increments of 0.003 inch”

b) From Canadian National Defence Manual “First Line Maintenance Instructions Rifle No4, all marks” dated 28th June 2002

Bolt head size 0 NSN = 1005-21-103-1143
Bolt head size 1 NSN = 1005-21-103-1144
Bolt head size 2 NSN = 1005-21-103-1145
Bolt head size 3 NSN = 1005-21-103-1146

“…….. the sizes being progressively larger in increments of 0.08mm (0.003”)


What Are The Results Of The Survey ?


Firstly points for consideration :
a) Used bolt heads will be worn and should be slightly shorter than new bolt heads.
b) The measurements were taken by many individuals, with varying measuring equipment. In quality control circles this would be totally unacceptable but for the purposes of this survey it is the best we can do, and does give results that demonstrate the point of the survey.
c) There have been instances where a bolt head falls way, way outside the expected (ie a size 0 measuring o.641”) and it turns out that some enterprising individual has ‘peened’ over the rear face of the bolt head by as much as 0.010” (10 thou) to tighten up the headspace, these measurements have been discounted from the results.

The numbers x1, x9 etc are the number of samples reported. (x1 = one sample, x2 = two samples and so on) Any further contributions will be gratefully received and the table updated periodically.

How often do we see the advert “Wanted size 3 bolt head” – hopefully we can now show that its not a size 3 bolt head that is needed – just a slightly longer bolt head.
Example (with sizes taken from the above survey) you have a size 2 bolt head that measures 0.630” but fails headspace by 0.003”, you actually need a bolt head that is 0.633”+ and this could be anything from a size 0 to a size 3

I don’t want to get into a headspace debate but we need to clarify what headspace we are looking to achieve.
The Enfield is a British Military rifle and it is they who set the headspace (if others want to set alternatives to achieve their own aims, then so be it). The headspace is specified at 0.064” min and 0.074” max.
So when measuring headspace ensure you use the correct gauges – the American SAMMI ‘field’ gauge is only 0.070” (The Sporting Arms and Ammunition Manufacturer's Institute (SAAMI) .SAMMI specifications call for a Minimum of .063" and a Maximum of .070" headspace in 30 calibres.) so you could be condemning a perfectly good rifle by using the wrong gauge.

The following are notes from Peter Laidler on proper use of headspace gauges and bolt head sizes :
Now that the gauge is into the chamber and the bolt is being closed, this is where the trouble lies. It’s important here to remember the often said phrase among Armourers of ‘DON’T OVER CHS’. Here’s another thing to remember during this. Because there is a camming action operating while OPENING the bolt, called ‘PRIMARY EXTRACTION’ this action also operates when closing the bolt. And the same primary extraction forces that will enable the infantryman to force the bolt closed and unlock and extract a possibly distorted shell case, covered in wet silt and mud in the saltwater Magrove swamps of Johore in Malaya that’s caused the case to stick hard to the chamber walls will also enable the butchers or bubbas to close the bolt hard against the gauge. NO-GO on the .074” gauge is when, using the lightest finger and thumb action on the knob causes a slight feel of resistance.
The next question you’re going to ask is ‘…where during the bolt closing movement is this slight feel of resistance acceptable --- Is it almost closed or, hardly closed or in between’? Good question and the answer in the bible reads thus: ‘…with a 0, 1 or 2 bolt head, there must be resistance onto the .074” gauge prior to there being a minimum of .050” from the underside of the bolt lever to the contacting point of the body socket’. Then it goes on to say ‘…….With a No3 bolt head the left edge…………..’ But I want you to forget this because the statement was too ambiguous. I suggest that you use my maxim of ‘WITH ANY SIZE OF BOLT HEAD FITTED THERE MUST BE RESISTANCE OF THE BOLT ONTO THE .074” GAUGE PRIOR TO THERE BEING A MINIMUM OF .050” FROM THE UNDERSIDE OF THE BOLT LEVER TO THE CONTACTING POINT OF THE BODY SOCKET. I want the master Masons among you to learn that by rote!
Using this criteria, if a No3 bolt head starts to resist half way closed and a No2 resists at .051” from the body side, then use the No2 bolt head. Remember DON’T OVER CHS
There are a couple of reasons for this. Firstly, it is from a point when the underside of the bolt handle is approx .15” from the sharp curve between the top of the body and the side of the butt socket, that the bolt effectively ceases to move any further forwards and is effectively locked.
The second is that prior to the point of fully locking, a feature called ‘mechanical safety’ comes into operation and (it’s getting technical now……….) the stud on the cocking piece will strike the stud between the short and long cam groove at the rear of the bolt causing a diminished force of blow to the striker, resulting in a miss-fire! Phew!
You will understand that this is a highly condensed précis of events taking in months of learning, investigating and examining undertaken by apprentices and I’m trying to cram it into a 40 minute lesson!
This brings me to another point………. It’s very basically this. If you cannot get headspace, even using the very relaxed criteria I have discussed here by using a new bolt and a No3 bolt head, then I’m afraid that it means your body is knackered. This quaint old Armourers technical term indicates that it’s seen better days ….., it’s xxxxed! You COULD allow yourself up to, say, .078” headspace but the technical opinion reached during research into this during the 50’s is that it’s a palliative and not a true cure.

Very few of us will have a bucket-full of bolt heads to work with so we need to have an idea of what bolt head size we need to overcome the headspace problem, headspace gauges will tell us it fails but not by how much.

A simple way, that gives a close approximation is by using a case and a primer :

Since the 303 headspaces on the rim, its headspace is the distance from the front of the rim of a seated case to the face of the bolt. To determine that distance we:
Measure the rim thickness of a new case. A fired case will have expanded and closed the headspace. You must use a new, i.e., unfired case. Measure around the rim and use the highest value obtained. For an example, we'll say it measures .062".

Take a fired primer and start it into the unfired case's primer pocket. Seat it just enough that it doesn't fall out.
Hand chamber the new case, and slam home the bolt, seating the fired primer with the bolt.

Remove the case from the rifle's chamber, and measure the distance the primer protrudes from the case head. For an example, we'll say it protrudes .014".

Add the rim thickness measurement to the primer protrusion measurement and you have your rifle's headspace, at least you have a close approximation of its headspace.
In our example, 0.062" + 0.014" = 0.076"


Thus if your headspace comes out at 0.076” and your bolt head is currently 0.630” then you’ll need a bolt head a minimum of 0.002” (two thou) longer but ideally somewhere between 0.002” (to give the 0.074” max) and 0.012” (to give the 0.064” min).
Instead of specifying “I want a number 3 bolt head” you can now look for a bolt head between 0.632” and 0.642”

Finally when changing over bolt heads consider ‘bolt head over-rotation’.

Check the bolt head to ensure it does not overturn by more than 20 degrees when assembled to the bolt.
The 20 degrees may be measured as 4.76mm (3/16”) from the left corner of the bolt head lug to the left corner of the bolt column.
An over-rotating bolt head allows all the recoil to be taken on the threads, with in few rounds your headspace will be back to where it was.

[mikld]

Lots of information, gentlemen. It's going to take me some time to digest it all (and search for other bolt heads). Thanks again...

[John Sukey]

Well, it's not the end of the world, there are several outfits that sell bolt heads, Numrich being one of them. Funny thing, of all the enfields I have and have fired, I never owned a set of headspace gages.

[mikld]

Well, I have since fired som factory ammo through it. Remington 180 gr. Core-Loct (semi-round nose). I covered the action/receiver with a small rug and fired one round. No kaboom. I measured the case, which extracted easily. The primer did not protrude. Case length was within .001" of an unfired case from the same box. Diameter of case just ahead of the extractor groove was within .0005" of an unfired case. So, I shot the remaining 18 rounds. What a hoot! Accuracy was so-so, with an unfamiliar gun, about 3" at 50 yards. Cleaning today; lots of copper in barrel. Oh well, back to the bench, and looking for components.

BTW, what's the optimum diameter for a jacketed bullet in a .318", 2 groove barrel?

[stratocaster]

Some really great info on headspace in this thread.

Moderators: Please consider putting this info into a sticky. It would save us newcomers a lot of angst about this subject that is not well understood for Enfields.

[Tom in GA]

Fiield space is .074 inches as stated above. Emergency headspace was allowed to go to .080 inches. I had a rifle with a headspace I gauged at about .078 inches. I shot a couple of UK mfg rounds in it. No problem except noted some black weepage marks on the case. I later fixed the bolt with a #3 bolt head from a #1 bolt head.

[Guamsst]

.......... Funny thing, of all the enfields I have and have fired, I never owned a set of headspace gages.

I think of Enfields like the SKS, if you can get a bullet of mostly the correct size and shape and a handfull of gravel in the chamber, it should function fine. I had a friend who religiously headspaced his Enfields and was fairly obsessed with it. He kept worrying about it and rarely keeping an Enfield due to all the headspace issues. I kept on collecting and on the rare chance I got one that was a bad shooter, it was always the barrel, not the headspace, that was the problem.