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S marked No.1 MkIII bolthead ?

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LE Owner View Drop Down
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    Posted: December 23 2009 at 3:04pm
I'd read in an Instructions to Armorers that MkIII Boltheads which were longer than normal were stamped with a S and set aside for tightening headspace if necessary and the standard BH wouldn't do the trick.
 
When I received my new Bolt Body and Bolthead I found a large S on the front of the extractor lug, and an SS on the underside of the lug.
 
The Bolt body is an unissued BSA 1950's production, new condition, the bolthead while I'd ordered it as used reblued looks to also be an unissued piece, finish is exactly the same as on the bolt body. Fit is as tight as a hatband with no overclocking.
I'd also ordered an extractor with spring and screw seperately, but the parts were already assembled when shipped, and look like they came that way from the factory.
Haven't measured its length yet.
 
Anyone know whether these S markings are those denoting the over length boltheads?
I did state in an Email before I sent in the order that I'd like the longest bolt head they had available.
I'm thinking they chose to send me a fully assembled unissued bolthead rather than a used one to be sure everything was as I wished. If so thats mighty nice of them.
The bolt head being pre assembled saved mea lot of hassle and possibly breaking an untried spring, which I did once years ago the first time I tried putting a new spring in.
 
Might as well throw in a plug for Springfield Sporters. They've always done right by me, and have a lot of high quality parts at reasonable prices.
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Lithgow View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lithgow Quote  Post ReplyReply Direct Link To This Post Posted: December 23 2009 at 3:28pm
No1 bolt heads were stoned to acheive headspace. Not sure about the markings tho.
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Alan de Enfield View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alan de Enfield Quote  Post ReplyReply Direct Link To This Post Posted: December 23 2009 at 5:00pm
Captain Peter laidlers comment :
 

Spare bolt heads issued from the factory were actually oversize and marked with a small ‘S’….., but nobody can tell me by how much! Other Armourers of the period have told me, only yesterday over a frantic phone call, that this is incorrect but they WERE all to the longest specification. Whatever it is/was, there should be room to stone to size. And THIS is where Armourers were always taught DON’T OVER CHS. Or in this case, should that read don’t UNDER CHS. If your rifle closes on the .074” NO GO gauge, this is what you do. Go to the No1 bolt head drawer and select half a dozen bolt heads that don’t overturn by more than 10 degrees (later, 15 degrees was permitted to make best use of remaining spare parts stockpiles), the bolt face is not ringed sufficient to allow the escape of gas past the primer and the striker hole is not greater than .084” dia. Try them all until you get the best fit. If necessary machine or stone the bolt head square and true until it closes over the .064” gauge and doesn’t close over the .074” gauge. The point at which the bolt doesn’t close prior to the .050” limit is academic because so long as it doesn’t go/close, it’s passed the test.

Now, how you shorten the bolt head it is up to you. You can machine it in a lathe if you like but some are quite hard, or surface grind but I was taught that the best way was to rub the face down on a sheet of ‘400’ wet and dry carborundum paper on a sheet of glass, just covered in slow running water. Go round and round with equal pressure, rotating the bolt head slightly every so often, taking a gnats knacker off at a time for several minutes and trying it again and again. Every so often, smear a smidgin of engineers blue on the rear of the .074” gauge and close the bolt head lightly against it to ensure a crisp round witness mark on the face of the bolt. This is the acid test of it being perfectly square to the bore. Be sure to remember these old Armourers technical words such as ‘gnats knacker’ meaning something too insignificant to be measured and ‘smidgin’, indicating a quantity equivalent to a gnats knacker.

That is very basically it! Once again, this is weeks of practice in the classroom and on the bench with discussion groups all put into one short period. And if we destroyed a rifle or bolts and boltheads while learning our trade ….., who cared so long as we learned and got it right eventually.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tony Quote  Post ReplyReply Direct Link To This Post Posted: December 23 2009 at 7:41pm
Thats sound advice as usual from Peter. I'll add this to the archives.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LE Owner Quote  Post ReplyReply Direct Link To This Post Posted: December 23 2009 at 10:18pm
Not sure what the above information means.
 
It doesn't explain the S on my new bolthead.
 
Perhaps the boltheads that came with the rifle from the factory and were already fitted to the rifle weren't marked, but spare boltheads issued for repairs would have been unaltered and bore the S to mark them as unaltered spares.
 
With the trading around of used boltheads perhaps new unissued boltheads were seldom needed.
 
My S marked BH closes on a unfired POF case rim, which usually measures from .061-.063. Seemed to take some slight effort, hard to tell since the new extractor spring is very stiff.
I may now have below minimum headspace, which is fine since I think the lefthand lug may have to wear in, or seat itself better with use, and most of my shooting will be with the thinner Remington Peters rims.
I don't plan to take any material away from the boltface, but it does seem to be not quite flat, like a very shallow domed appearance, which might be an optical illusion.
 
I may send the old bolt body to a gunsmith who works on Enfields and let him see if he can find a bolthead with oversized threads to make up for the damage done by the oversized firing pin flange, aside from the worn threads the old bolt body was fine. Had this new bolthead fit the worn threads of the old body better I wouldn't have switched out bolt bodies.
 
An oversized firing pin flange/collar whatever, is something to watch out for. Whoever assembled that bolt must have been in a hurry.
 
As it is I think I'm on the right track to best performance, depends on whether the lug bearing equals out with use.
I'd prefer not to lap it, since I may want to put the old bolt back in it one day.
 
From examining well used Enfields it seems the bolt lugs are just a hair less hardened than the seats in the receiver. Which makes sense, a bolt is easier to replace than a receiver so you'd want the bolt to wear before the receiver/action body.
 
The oddly rough surface of the lefthand lug seems to indicate those were left unfinished to allow some stoning to fit.
 
Since the bolt knob has the BNP proof mark I would think the lugs are already hardened.
 
The old bolt had smears of copper near the lugs, the new bolt has no such marks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alan de Enfield Quote  Post ReplyReply Direct Link To This Post Posted: December 23 2009 at 10:40pm
LE Owner, Maybe I'm having an off-day but I'm not following what you are saying,
Your new (unfitted) bolt head has as S
I think that it what Peter is saying - spare oversize bolt heads were marked with an S
 
"I may now have below minimum headspace, which is fine since I think the lefthand lug may have to wear in, or seat itself better with use"
This isnt quite the correct way to do things - see below.
You can of course just stick a new bolt in and fire away, but to avoid damage to the locking lugs from unequal 'recolil' you do need to fit a bolt correctly.
 
Here are some more notes from Peter Laidler which hopefully might help.
 

First things first. Bolts could only be fitted at Field and Base workshops because they were the only ones that had a 'GAUGE, Inspectors, Bolt'. This is a brand new, calibrated bolt. Still in white metal and marked as such. If my memory serves me right, the slot in the long/top locking lug is machined right through to identify it. So that's the reason if you have ever seen one. This bolt is bare. Clean the locking lug surfaces of the rifle and put a smear of 'engineers blue' marking dye onto the corresponding locking surfaces of the inspectors bolt. Insert this bolt RIGHT FORWARD, rotate it closed, then draw it backwards and forwards a couple of times to mark the mating locking surfaces of the rifle. Push it forwards, unlock and remove.

Examine the locking surfaces of the rifle. The blue witness marks should be evident. This ensures that whatever wear that has taken place on the rifle locking surfaces has taken place equally. If its not, then I'm afraid that the rifle is unserviceable.

BUT, that's not quite the end of the story because you won't have this 'Gauge, Inspectors, bolt' but it's only right that I tell you. Now for a little secret. If you have ever bought a rifle that has a sploge of red paint on the left side, adjacent to the internal left side locking lug, then you now know that the rifle was condemned for 'worn locking lugs'.

If you are going to fit a second hand or new bolt, then do the same thing. If the dye pattern is one sided, then stone the high surface of the bolt until BOTH locking lugs bear evenly against the locking surfaces of the corresponding surfaces in the body. BUT DO NOT ATTEMPT to stone the rifle to get a bolt to fit (you can only get to the right hand surface in any case ....). The rifle body is induction hardened at these points to a depth of .004 - .006" but we have found it deeper.

Now that you have got the bolt fitting, with the locking surface bearings matched, it's time to fit a bolt head. Any one will do. Screw it into the bare bolt and test the CHS against the .064" GO and .074" NO GO gauges.
 
Hopefully you have correctly 'fitted' your new bolt & bolt head to the rifle.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lithgow Quote  Post ReplyReply Direct Link To This Post Posted: December 24 2009 at 6:40am
In Peters case, they had lots of bolts and boltheads.
We do not have such luxuries.
I have been taught to fit them by my father and it is exactly as Peter has described but alas, I dont have a dummy bolt.
The locking lugs on a new rifle were not fitted by hand, when the rifle was proof fired, this set the lugs into the seats of the recesses.
Checking the fit of the lugs was also part of the accurising process on target rifles.
When fitting another bolt body to a rifle, people always think headspace is important but thats only part of it. the other part is the fit of the lugs and this is as important as headspace. The rifle was designed to have two locking lugs bearing.
As far as bolt heads go I have seen some of them so hard on the face that they cant be drilled or machined.
Merry Christmas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LE Owner Quote  Post ReplyReply Direct Link To This Post Posted: December 24 2009 at 10:35am
This was the part of the previous post I fond confusing.
Quote Other Armourers of the period have told me, only yesterday over a frantic phone call, that this is incorrect but they WERE all to the longest specification. Whatever it is/was, there should be room to stone to size.
He seemed to be saying that the armorer he spoke with was saying there was no S marking of an over length bolt.
And what I figured had happened was as I wrote that perhaps only bolt heads intended as replacements had the S, the BH originally fitted to rifles before proof would have already been shaved down if necessary and wouldn't have the S, because they were of varying lengths.
Armorers in wartime, or times of short funding might very seldom, and perhaps never, need a S marked head, since they had many used ones to sort through to find a decent fit.
 
I agree with Lithgow that equal bearing is necessary for good accuracy, and probably safety for that matter.
Older works on the LE make it plain that this is so.
 
I intend to do some spotting and if need be stoning. I have a wide assortment of hard arkansas stones I can choose from.
I'm not jumping in till I know more though.
When closed on a thick rim the visible gap closed, and this seems to be because the bolt had been tilted.
I want to look into that further.
The new parts tight fit may be a hair too tight, not letting the bolt settle into place normally. It could go away with a bit of cycling the action to smooth it out.
Any stoning would be to the bolt lugs, not the action body lugs.
 
As Lithgow says, the proof loads did the final setting of lug surfaces, this is true with every bolt action type I know of, no hand stoning can garantee a perfect fit, you can only come close enough that undue strain isn't transfered during the setting process.
To some extent older actions will show better seating due to normal wear.
 
The lefthand lug still has a rough surface, with a slight indentation in the center, no more than a few tenthousandths deep.
The right lug contacts at the bottom, the action body surface showing the not uncommon slope of a couple of degrees, perhaps due to wear, but older sources say this was due to compression during proof.
 
I'll fiddle with it a bit before stoning anything, should the fit look pretty close I'll testfire a few rounds, and see if that works to settle it in better.
 
Most actions I've seen show some signs of upsetting of the metal of the bolt lugs, generally the right side. Not much, just enough to indicate it conforming to the locking surface of the action. Whether during proof or from repeated firings I can't say, certainly after finishing the metal .
 
The threads in the bolt body seem more prone to damage than the threads of the bolthead. The method of removing or installing the firing pin is probably the reason. 
If an oversize collar or burrs aren't stoned down the threads can be damaged trying to force it in.
A bent pin shank might also cause a problem during installation.
 
I'll know more when I find my spotting pen, I saw it last week, but can't remember where.
 
 
Could be the S means something entirely different on this BH. Possibly a subcontractor.
 
 
PS
I checked the boltface, its flat, the domed look was an optical illusion due to the concentric polishing marks and radiused edge.
 
Since when closed on a thick rim the gap disappears I'm figuring that firing a few rounds that have thick rims should settle it in. The surfaces would be near flat to each other then so it wouldn't take much to set them.
 
 
PPS
 
Sucess.
After the kids had all gone home after the party I just had to do something to keep my mind occupied.
After a couple of false starts, I finally got it figured out.
The finish milling of the lugs had been a hair sloppy, instead of the lug surface making contact only the edges of the locking recesses were contacting the corners where lugs met the body. I sharpened those corners just a hair, much more so in one corner where it had a lumpy apprearance, then managed to get the lugs both making some noticable contact at the same time.
 
By that time I couldn't sleep and already had my stuff laid out to go for a testfire in the morning, so I took off about 1 AM and found a quite spot not far from here. No one was going to be around even if it had been daylight because a hellacious windstorm blew up.
So I fired only one round of a fairly hot load I only use in my No.4. Don't plan to use it in the SMLE but it served as a minimum proof round, and the lugs now make a bit better contact, near as good as the old bolt from the first outing. They should now wear in nicely they already seat equally.
 
Haven't formally checked headspace but got a couple of suprizes.
The headspace with new bolt is definitely better, I tried the old bolt and it closed without noticable drag on the fired case, while the new bolt closed with some noticable resistence.
The improvement may be only a few thou, but its all good.
The fired case looked good, no annular ringing.
 
The big suprises were that the old bolthead turned out to be the longer of the two, while the old bolt is the shorter of the two.
 
Also earlier I hadn't tried to screw the old head into the new body more than halfway, it had seemed very loose up till that pint so I dodn't bother turning it in further. I tried again and found that just past the mid point the old bolt head threads were less worn and its way to tight for the new body, it could be force fitted but that would loosen the threads of the new body.
So if the new bolt suffers any noticable set back I could tighten headspace again using the old bolthead. That was a pleasant suprise.
The wear of each must be more at the rear for the old BH and more at the front for the old BB.
 
I'll probably still try to find a bolthead with larger diameter threads for the old bolt one day, but for now I figure I've got something good going. 
From the looks of the fired case these should have a long caselife.
 
I'll smoke and check lug contact after every shooting session. When contact lokks completely satisfactory I'll then formaly check headspace, till then so long as it closes on a thick military rim yet allows reloading of thin rimmed commercial cases I'm not that concerned.
 
 
BTW
I'd first read of the need for equal bearing in relation to the old Log Lee rifles. They stoned the lugs to match as near as possible before proof testing.
I don't doubt that stoning was not done too often during wartime production, too time consuming and requiring skilled labor.
They may have simply depended on setback to take care of it.
 
Only problem there is that it could result in the proofed bolt body not sitting square to the lugs and a hair out of the centerline of the bolt way. Could also unduely stress the bolthead shank I suppose.
 
Best to be sure both lugs make contact first, otherwise it could end with equal contact but an out of line bolt.
 
 
 
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Alan de Enfield Quote  Post ReplyReply Direct Link To This Post Posted: December 25 2009 at 12:40am
Well - glad its worked out OK for you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LE Owner Quote  Post ReplyReply Direct Link To This Post Posted: December 25 2009 at 2:38am
I'm pleased that I didn't screw it up, and learned something by observation at the same time.
 
I may have mentioned the rough and uneven locking surface of the lugs as received, in contrast to the nicely finished rest of the bolt body.
 
It would appear that these replacement BB require significant hand fitting to get a good fit, not just evening out the locking surface interface , but also the body of the bolt around the edges of the lug.
 
What I'd taken to be interference from the extractor spring pressure was in fact binding of the unfinished area behind the lugs with the inside surface of the bolt track at that point as the bolt is rotated home. Had the action body been worn or the bolt a looser fit the binding wouldn't have been noticable.
When I'd closed the bolt on the thicker POF rim, with some difficulty, there was enough back pressure to forcet and close the gap, that should have tipped me off.
Not finding my spotter pens lead to smoking the surfaces with a candle, and the true source of interference became easily visible.
 
So I'd advise anyone fitting a new bolt body to check for binding as the bolt is rotated before going further.
 
I seem to have gotten a decent fit without much removal of material, just enough to smooth down and mate surfaces to recesses.
 
I've occasionally run across good rifles with missing or damaged bolts, and barreled stripped receivers are often advertised. With a spare bolt that I can restore to service I may order up a stripped receiver for a sporter project later on.
 
PS
I guess this at least settles the question of whether an S marking on the extractor lug denotes a longer bolthead, in this case the S marked BH is shorter than the unmarked head.
The S marked head was ordered as used reblued, so it may have been shortened at some earlier time.
The unmarked head is of the older type with a scallop cut, could be these older types are often longer or had larger threads which could be why it was fitted to the older bolt to take up slack.
 
I'll try checking all my boltheads with a dial caliper soon to get a better idea of what to look out for.
 
 
Also
The Instructions to armorers section on boltheads
Quote

7. To fit new bolt-head to Rifles No. l.—(Spare part bolt- heads, marked "S" on the top, are longer at the front.) Assemble the bolt-head to the bolt, insert it in the body, and test with .064-inch No. 1 gauge; should the bolt not close over the gauge, remove the bolt-head from the bolt, and having placed a piece of emery cloth (No. F) on a flat surface, rub the face of the bolt-head on the emery cloth, maintaining a circular motion in order to preserve a flat surface, until sufficient metal has been removed to enable the assembled bolt to close over the gauge. The bolt should not close over the .074-inch No. 1 gauge. Care should be taken to keep the-face of the bolt-head flat and square. After fitting and adjusting, the top front edge of the face of the bolt-head is to be rounded to a radius not exceeding .02-inch.

Note.—When it is found that the bolts of several rifles turn over the 074-inch No. 1 gauge, the bolt-heads should be ex- changed among such rifles, as, owing to the varying lengths of bodies and bolts, bolt-heads which are too short in one rifle may be serviceable in another. Bolt-heads that have been replaced in rifles by longer ones, should be kept by the armourer and used whenever possible in rifles requiring the bolt-head replaced, so as to avoid unnecessary use of new spare part bolt-heads. Part-worn bolt-heads held as required by armourers in accordance with the foregoing need not be accounted for as part of the annual allowance of new spare parts.

 
The bolthead I got has the s on the front of the extractor lug, not on top, so this S must have a different meaning altogether, perhaps a subcontractors code. It also has two larger S on the underside of the lug.
The S marks are much deeper than the rest of its markings.
I'd like to find out just what these do mean. A bit confusing still. 
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