No 4(T) Faz

[GeeRam]

I didn’t realise they even made a four bolt head, I always thought it went 0,1,2,3?

That was my under standing as well. I have a vague memory of PL writing something on here about them making a tiny batch of number 4 marked heads to test viability of extending the life of some knackered rifles, but ended up ditching the idea.

[Roger Payne]

I don't doubt what Peter said, but that was late on in the career of the No4 rifle. I'm referring to factory new rifles made when we had our backs to the wall during the war. Just wish I could remember where I came across the info. I'll have a rummage.

[Micheal Doyne]

That would be very interesting, points to a bit of QC issue does it not. If assuming rifles where intended to by 0-1 if they need 3+ at initial completion, to a sufficient degree it was worth the manufacture of 4s?

[Alan de Enfield]

That was my under standing as well. I have a vague memory of PL writing something on here about them making a tiny batch of number 4 marked heads to test viability of extending the life of some knackered rifles, but ended up ditching the idea.

What PL wrote was that factories were not allowed to fit a No3 bolt head.

In 2007 :

There is a little more you might need to understand before you can appreciate the whole picture. The No4 rifle was a very precisely made piece of gear. The very fine production tolerances achievable meant that every rifle could be assembled with any parts from production within set tolerances and be correct for headspace with either a No0 or a No1 bolt head fitted. To leave the factory, that was between .064" and .068" headspace. If a rifle failed headspace in service (failed the "field" gauge at .074") Then it was sent back for repair. If it could be headspaced with the next size bolt head (either a 1 to replace a 0, or a 2 to replace a 1) it was deemed good to go. If a rifle did not pass headspace with a No2 bolt head, then it was passed up the line to the senior inspector who would apply the Gauge, Inspectors, Selected Breach Bolt. If the receiver passed the test, it could be fitted with a No3 bolt head and put back into service.
NOTE HERE. A NO3 BOLT HEAD WAS ONLY TO BE USED ON THE SAY SO OF THE SENIOR INSPECTOR.
If it did not pass the test, it would have been sentenced Z for return to the factory, (even if a No3 bolt head would pass headspace)


And in April 2008 :


I was having a chat to one of the most senior examining Armourers at a huge Base Workshops at Warminster a few days ago. Long retired, he was a 1930's apprentice and one of the very strict examiners. I was asking him about chroming bolt heads to get longer life out of heads bolts and bodies when he reported back something that was VERY interesting.
He said that during the mid 50's, there was a plan mooted to make a No4 size bolt head available so as to decrease the number of old wartime/tired/just plain worn out rifles being condemned as unfit simply because of excess CHS. The alternative was to increase the MAX CHS to .078".
He was involved in this project as the research Officer, so was in from the start. The PROBLEM was that once the BOLT, Inspectors, Gauge (a calibrated slave bolt used to test wear) plus a calibrated No2 bolt head (No3 not permitted at Base/Factory don't forget) had been inserted into the inspectors gauge bolt, then making a further bolt head available was palliative and not a cure because these simple tests indicated that it was the BODY that was worn and not the bolt or the face of the barrel. And thinking about it, while it's obvious really, it's absolutely correct!

[Micheal Doyne]

Thanks for that!

So not for new prediction rifles, and not implemented, that clears that one up then

Cheers

[Surpmil]

Generally yes, but 4's & even 5's are seen very occasionally. They were not standard issue so far as I know. I think I read somewhere that they may have been a factory expedient to allow rifles to be fielded that might otherwise have been rejected by the examiners. My rifle has been given an 'A' suffix suggesting it was noted to contain non standard components..........perhaps indicative of the over large bolt head? Incidentally, I'm pretty sure of the rifle's provenance & all of the bolt appears as per factory issue. The bolt head is clearly marked with the stylised 'M' typical of Maltby rifles & components.

Yes, the dangers of saying "never" where Lee Enfields are concerned:

https://www.milsurps.com/showthread.php?t=9026

https://www.milsurps.com/showthread.php?t=6969

https://www.milsurps.com/showthread.php?t=64318

https://www.milsurps.com/showthread.php?t=36266

https://www.milsurps.com/showthread.php?t=53886

And given the WIDE variation in actual lengths of the various bolt head "numbers" that has now been documented in Alan d'Enfield's spreadsheet, one can probably conclude that swapping in bolt heads by "number' is almost pointless.
Of course we don't know if or how much the bolt heads in the spreadsheet may have been altered over the decades since they were made, and presumably there was a mixture of new and used on hand in most Base Workshops?

This Gauge, SM338 appears to be one that would be used, either in conjunction with the "gauge, master bolt"(?) or with the rifle's own bolt?

Somewhat surprising, but the way this sentencing process has been described by Peter in the past it sounds more like the practice was to swap bolt heads around and if no No.2 could be found that headspaced, the rifle was sentenced "BLR" and sent for examination with the gauge, master bolt at a higher level workshop?

A rifle of course can hardly become unsafe because its lugs are a few thou shorter than they were previously.

And that's leaving aside all the other variations in relative dimensions and positions between the front face of the body and the faces of the recoil lugs, to say nothing of the location of the chamber cone relative to the rear face of the barrel which the HS gauge sits on, etc., etc.!

(Parallel discussion here: https://www.milsurps.com/showthread....817#post487817 )

[Alan de Enfield]

Of course we don't know if or how much the bolt heads in the spreadsheet may have been altered over the decades since they were made, and presumably there was a mixture of new and used on hand in most Base Workshops?

Yes I'm sure that some boltheads were 'altered' to be fitted, but in military use it would be far simpler just to get a handfull and try each one, rather than grind down one to fit (unlike the No1 bolt heads that were all manufacrured over size).

My thinking is that 'making a bolt head fit' would (I would have expected) involve 'shortening it', in which case why are there #0 bolt heads larger than #1, #2 and #3 measured - were all those ground down/ or were some of the #0 made 'big'.


The #4 that Roger owns measures within the #3 range in my spread sheet, so again, an anomoly - why make a #4 the same size as (and smaller than some) #3 bolt heads ?

Did each manufacturer #0 start at different sizes ?

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”)


If only we had 100's of bolt heads to measure and compare.

I cannot find my latest spreadsheet ( it was a few years ago and had a total of around 300 samples), but, this version is enough to prove the point.

[Surpmil]

Logically a gauge, bolt head (perhaps the one shown above?) would have been inserted in the bolt body and closed on the HS gauge. Doing so would give some consistent point of comparison/reference for that particular body>bolt>barrel (aka, headspace) combination.

One would assume that no attempt was made to fit a different bolt to the rifle body until the "Gauge, Master Bolt"(?) had been tried with some gauge such as that above, to determine if a new bolt would solve the problem? Particularly since the contact of the bolt lugs would have to checked and adjusted in an irreversible hand-fitting process, before one could tell what kind of HS the replacement bolt body could even provide! And that's not even touching on the variation, if any, in the lengths of the potential replacement bolts!

So the question becomes: were the bolt heads actually measured with a micrometer in the workshops to determine if they were within the standard for their size number, or were they just treated as though "a No.2 is a No.2", with some variation borne in mind, and selectively fitted until one was found that met the minimum standard for HS?

In that case, one might well end up with a rifle that was accepted, not because it's bolt head was within spec for it's size number, but only because the bolt fitted happened to be a bit longer than many, or the rear face of the barrel, or the positioning of the barrel threads and front face of the body happened to be a bit shorter than some others! And if so, conversely others might have been rejected for such variations in the "minus" direction?

Again, from what I recall of what Peter has said in the past, it doesn't sound like micrometers were used to measure the bolt heads, or that a gauge such as the above was used initially, and therefore there was apparently no reliable way to establish the ACTUAL distance between the body recoil lugs and the back of the HS gauge until the use of the "Gauge, Master Bolt" (?) at higher level workshops?

The point of all this is that there are numerous variables in this equation other than the length of bolt heads, and personally I fail (thus far) to see how the wear of recoil lugs, or their length, could be determined by measuring headspace since AFAIK there is no dimensionally reliable point of reference on the bodies from which to do so, without removing the barrel.

Obviously it would be uneconomic(?) to rebarrel rifles to obtain correct headspace, although gunsmiths do this every day in Mausers and other rifles with fixed bolt heads.

Slightly tangential:

I recall Peter has reported that a study was done of body lug hardening which found that it was very thin, somewhat inconsistent, and could wear through. It would be interesting to know more details of how that was done.

The problem I have with this is that induction hardening is said to usually be very thin and superficial, and yet the hardening of the smaller lug clearly penetrates through the body side wall and the lug which together are almost 1/4 inch thick. The area hardened was also large enough to interfere with the drilling of the screwholes for the rear pad of the No4(T). On the larger lug, I have several bodies on the desk in front of me, which show a hardening discolouration extending 3/16 to 1/4 back from the front face of the lug.

One could argue that the hardening on the larger lug is superficial despite extending back as far as it does, but how do we explain the smaller lug, where the hardening has either been applied from the bolt way and the body side simultaneously (and why would it be?) OR it has penetrated right through, in which case how can it be superficial? And if it is not, why would it be on the larger lug either?