Lee Enfield chamber reaming in the Great war?

[Lee Enfield]

...snip...
The Lithgow rifles had the bolt carriageway reamed to allow more clearance, as sand was binding the close tolerance actions and the increased leadin bevel was also done.
British actions had more tolerance in the chambers than the Australian ones,
...snip...

My understanding was/is that in 1915 the tolerances were changed due (mainly) to experience in Palestine.

Supposedly the original SMLE bolt diameter minimum (-) was changed to become the standard, the standard dia was changed to be the max (+) diameter acceptable tolerance.

At the same time the standard bolt race diameter was changed to be the minimum (-), and the max (+) was changed to be the standard diameter.


This is supposed to be the reason why pre-1916 SMLE actions were preferred as the donors for the Australian HT program during WW2 (because they are toleranced tighter, not because they "Flexed better").

[Son]

Here is another quote from the same forum and the same "moderator". I was reminded of this one from the comments above about how clever you have to be to ream a chamber into an oval shape.... well, here is another magical myth of machining wonder!

.303 Military brass has a very thick web in the casing which when fired in an Enfield rifle with excessive head spacing may not show any signs of case stretching. When the shooter tries a commercial loaded round and sees a bright band or an " hour glass" shape just in front of the rim, they assume that the brass is somehow faulty. Not true. It is your rifle. Any time you see a stretch mark or the case fails and parts in two just in front of the rim, its caused by excessive play. 8 of of 10 ten times it is excessive head spacing. The other causes are a too long chamber where the case is " blown out" to fill the shoulder area, or the chamber is out of round, drilled off center. Beleave it or not, this is not uncommon with these rifles. You gather up 10 Enfields and you will see fired cases from a couple of these rifles that show and off center / out of round chamber.
Why? You need to understand that these rifles were made in the time leading up to, or during a time of war. The British Army needed many,many rifles and needed then quickly added to the armories. Quality suffered as a result. The rifles were well used and showed up in all sorts of places after the wars. How and what was done to them is any ones guess.
Years ago I had a chance to spend some time in England. I met a fellow who was a British Army Armorer. He and I talked over beers about rifles and all sorts of WWI and WWII weapons in general. I brought up the topic of head spacing in the Enfield Rifles. He told me that they were taught to " To provide enough head spacing as to allow the soldier to carry a dry pair of socks" in these rifles. The reason being war time production of ammunition and the very different climates these rifles were to be used in. I asked him how they adjusted the head spacing, did they use the numbered bolt heads for the No4 rifles, or the varying length No1 type bolt heads to adjust the head spacing?. If they could get them,yes. But the number they needed was not always available out in the field. 95% of the time the bolt body was shortened

[Richard Hare]

Well me old Son,

I don't often sit here with my mouth open, but that's what you had me doing when I was finished reading this!!
Still am for that matter.

It's the sort of thing that brings on a response of dead silence or "eh??"

R.

[Mk VII]

p.203 of The Ross Rifle Story reproduces (rather poorly) a blueprint (yes, a real 'blueprint') showing 'Lee-Enfield Chamber' ("original size RSAF plan No.3066") as .459 at the entry and 'Lee-Enfield Enlarged' as .462 at the entry. A note at the bottom says "New Lee-Enfield slightly larger than Lee-Enfield enlarged but not as large as Ross". The text states this as dating from prior to mid-1911.

Ross, in a letter to Carson dated Aug. 1916 gives the dimensions of the L-E chamber at that time as:

base of large cone .462
small end of large cone .404
large end of neck .343
small end of neck .339

these figures appear to be the same as those in the 'Lee-Enfield Enlarged' quoted above although the reproduction makes it somewhat doubtful to be certain.

Another drawing of an experimental RSAF SMLE chamber, dwg. no. R.O.208 of 2/5/16, is shown, marked 'enlarged chamber' so they were playing about with dimensions as late as then. Unfortunately the figures do not reproduce well and the gauging points may not be the same.

A chamber dwg, stated as being the rifle chamber, is reproduced on p.250 of the 1929 Textbook of Small Arms and gives:

base of large cone .462
small end of large cone .404
large end of neck .345
small end of neck .341

[Bruce_in_Oz]

By those numbers, we are looking at "variations" in the realm of 3 thou. or less, about what you would expect from reamer wear on a large "RUSH-JOB".

Has anyone run a set of bore gauges, (the dinky, adjustable ones that look like a rod with hard steel balls that can be adjusted in and out by twisting the end of the handle), in a "mint' SMLE chamber lately? Might need to do some number-crunching due to the serious taper on the "large cone".

The only "mint" barrels I have here are a couple of Lithgow "heavies", circa late 1950s, still in their sealed packaging.

[Bindi2]

B i O a question. Any H barrel i have had or had anything to do with has all ways been a small or tight chamber. This also applies to Ts. So were these cut with worn out reamers or in the case of the Ts selected because they were more accurate than new reamer cut barrels.
Peter your input as well please.

[Thunderbox]

You do find SMLEs where there is very excessive shoulder space in the chamber, but nothing to suggest that the entire chamber has been relieved. In the most extreme case I've had so far, the case shoulder would fireform a good 1/8" forward, removing half of the neck of the case. It looked very odd! It looked a bit like a .303 Epps, but with with standard .303 taper and shoulder shape. That rifle was perfectly tight for headspace, however, and had a good lead and bore. No other sign of distress or distortion on the cartridge case.


Presumably, if chambers had been altered, there'd be both some sort of printed field instruction, and an official indicator mark on the rifle to show that the work had been done?

[Bruce_in_Oz]

Just to make things more interesting:

SMLE (and previous Lee Enfields) had their chambers formed, not by running in a slinky Clymer or PT&G one-piece reamer, but by a series of operations involving the use of what appear to have been "D" reamers.

Because of the limitations of these rather rudimentary tools, the chambers were cut in stages, with the neck AND the "leade" (throat) being cut LAST, using specialised reamers and gauges.

By the 1920s, one would hope this had changed, although, to the end, apparently, the final chambering operation was the firing of a "special" proof cartridge to "set up" the barrel / body "fitting" and the mating of the bolt lugs and the locking shoulders in the body..

One has to ask:
1. What were the other "Majors" using in their factories at the time?

2. Did this caper continue on into the No4 series?

Given this method, is it any wonder that HM Ordnance opted for a rimmed case; at least this would have provided SOME fine control over breeching.

In the previous Snider and Martini Henry rifles, the service ammo had a case made from a steel "base washer" and a rolled brass foil body to contain the powder and bullet and provide some semblance of a "seal" on firing. This ammo was not as flimsy as it sounds, but would work in almost any "appropriate" chamber, cut by whatever method, as long as the bullet could enter the throat / leade. Only a short hop from rolled paper cartridges of just a couple of years before.

The Martini Henry went into service with such "composite"ammo at about the same time several other countries were fielding rifles with smaller bores, and cartridges with one-piece, deep-drawn brass cases. As they say in the classics: "What were they thinking?

Also bear in mind that serving alongside the Martinis, was the Gatling gun, with a "proper", deep-drawn cased .45 calibre cartridge, different from and NOT interchangeable with the rifle ammo. There is NO way the antique, rolled-brass cartridges would have stood up to the stresses of being fed, fired and extracted through a Gatling, at almost any rate of fire. There was enough of a problem conducting sustained fire from a Martini Henry, especially once black-powder fouling started to build up.

[mike1967]

.303 Mil . I asked him how they ad. If they could get them,yes. But the number they needed was not always available out in the field. 95% of the time the bolt body was shortened[/QUOTE]

Surely not, the threads still remain in the same place, and what about overturn.

[Bindi2]

My understanding is the bolt head face is ground/stoned to give the correct head space not the bolt body.