No1 Mark 111 Breaching up

G'Day,
Is the procedure for breaching up the No 1 different to the No 4, as after reading the article by Mr Peter Laidler I am confused as to which face is the breaching up face. The No 1 breaching up face is the end face of the barrel, as the shoulder is actually clearance. To machining for instance .100" off the breaching face would actually shorten the chamber and remove the extractor slot.
Also in regard to using steel shim, page number 37 in the Ian Skennerton book "Australian SMLE Variations" list the part number B2BBA440 and BBA4401 for .003" and .005" Washer, shim, steel. Is this an Australian practice only to fit steel shims for breaching? I agree 100% with the statement about peening the shoulder over as the local gun dealer uses this method with various degrees of success. Locating the barrel of the shoulder would result in clearance at the breach face.

Hope this makes some sense,
Rastis.

No4's breech up on the shoulder, unlike the No1 which as you say, breech up on the face of the tennon.

G'Day,
If the correct procedure for breeching up a No 1 is to use a steel shim between the barrel breech face and the receiver (if the barrel tightens up with a overturn), then if the barrel tightens up with a underturn do you machine the face of the barrel or the receiver to correct this. Machining the barrel end (breech face) would be significantly easier then machining the receiver, though you would be reducing the chamber length.


Rastis.

I doubt you'll get them tightening up with underturn, I have never heard of anyone needing to do this.

G'Day,
Thanks, Bonesmith. I like to know how things work before I get someone to do a job for me. If you ask people how they are going to do a job, and you don't know anything yourself, they can be telling you anything.

Rastis

A couple of things about SMLEs:

According to my 1945 copy of the "Identifications List for the Rifle, No1 Mk3 and 3*" in Australian service, there was, at that thime no internal breeching washer on issue.

Barrels, both light and heavy were made with their breech threads qualified to a gauge (part number as yet not known). In the 1950's, as the rifles were getting a bit tired and about to be phased out, a "replacement " barrel was apparently introduced. The difference was that the thread indexing was advanced (7 - 11 degrees??) so that it could be pulled up dead square, and at the correct torque, in a "pre-loved" receiver. Note also that at this time, longer boltheads, a la the No4 series, were introduced. The whole idea was to squeeze the last bit of life out of some weary rifles.

Not sure about Britain and Canada, but Lithgow also produced two "grades" of No4 barrels to suit new and "used" No4s. The difference is in the nominal thread start point. These appear to have been for the rifle clubs as they have no bayonet lugs. (Drawing number: U-52831) The latest date on my copy of that drawing is 12 March 1965.

If a brand new, fresh out of the bag Lithgow "H" barrel goes to, or past top dead centre under hand pressure only, the receiver threads are probably a bit sad.

Further to my last about breeching washers:

Canada DID issue breeching washers for No4s at least as late as 2002.

Three thicknesses: .002", .003" and .004" They even have NSNs (the 3 thou job is 5365-21-111-7248)

See C-71-111-000/MY-000,
"PARTS IDENTIFICATION LIST
RIFLE, .303 CALIBRE, LEE ENFIELD, No 4,
ALL MARKS"
Does anyone have late Oz EMEIs (WPN D110 Decade) for field/medium repair of SMLEs? That's where any reference to breech washers should be.

Bruce,
The part numbers for the breeching washers came from a 1978 Repair Parts List for the .303 Rifle No.1 MK 111*H.T. It is reprinted in the Australian S.M.L.E Variations by Skennerton. What you say makes sense as I have a 1919 Lithgow that when fitted with a selection of second hand H barrels hand tighten at either the correct finished position or past it. Thread stretch and wear would account for this. If you want to send me a new H barrel to try so I can see where it tightens up at PM me:lol:
I think .001 wear on the breech face will give you approx 4 degree's positional error.

Thanks,
Rastis.

Breech thread: 14 TPI
Therefore pitch: 0.071428"
Advance per degree: 0.0001984"
Advance per 4 degrees: 0.0007936"
Advance per 12 degrees: 0.00238"

As you can see, it doesn't take much wear / crush, to wreck the thread indexing. "Conventional" threads crush both radially and linearly.

There's a lot to be said for the "square" threads found in the P-14 / M-17, Springfield, M-1, M-14 etc., although they are not as good at "self-centering".

G'Day,
Do you know what thread profile is used. A 1" UNF thread will screw in firmly, but I doubt the poms would have used a 60 degree thread.

Rastis.

Rastis:

SMLEs and all before them, martinis included, use an "Enfield Special" thread.

Whilst it may be 14 TPI it is neither Whitworth, BA or UN in form.

Details are as follows:

Outside (Major) diameter: 0.9955"
Root (Minor) diameter: 0.9024"
Effective (Pitch) diameter: 0.9574"
Pitch: 0.0714" (14TPI)
Angle (included): 49deg 40 min.
Root radius: 0.00804
Crest Radius: Unknown (I will load all that lot into my Cad system and do some creative geometrry)
Note that the crest radius is defined as being 0'01949" from the nominal crest height.
I have seen "sporters" with No4 barrels "fitted" to SMLEs and vice versa. Not sure which vise is versa, though.

Given the available metrology of the times, keeping to 5 decimal places must have been interesting, especially in mass production.

EVERY other thread on a SMLE is a "gunmaker's special". The only one close to "industry standard" is the stock bolt, which is listed as to 7/16 Whitworth but may be slightly different in form.

On a No4, every screw is "industry standard" of the day. Almost all are various BA sizes. The front triggerguard screw is 1/4" BSF.

No4 Threads are DEFINITELY Whitworth form.

P-14s are also full of weird Enfield threads; most definitely not UNF/UNC.

Posted too fast:

"No4 Threads are DEFINITELY Whitworth form." should read "No4 Threads are DEFINITELY NOT Whitworth form except for that 1/4"BSF job

Going with "general engineering" threads made sense when involving thousands of subcontractors in wartime production. Managing the "Peddled Scheme" for SMLEs in WW1 must have been a nightmare to provide all the gauging right down to simple thread level. Specialised tooling would have been nececessary to make even the most basic screws in the rifle. How many basic lathes can cut 37TPI without a lot of fiddling in the gear train? However, every man and his dog would have had a set of BA tools and gauges. These days, CNC lathes can easily make any weird thread pitch you like; it is sometimes a struggle to get the operators to actually grind the correct form tool.

Bruce,
I wonder how many barrels have been threaded either 55 or 60 degrees because that was the tool the gunsmith had in the lathe at the time. 49deg 40 min is certainly an odd one, Its not even 47.5 degrees that BA is though.
Apparently a No 1 barrel when screwed into a No 4 action indexes 180 degrees out.

Thank You,
Rastis.

The thread form on the barrel drawing looks a bit like a BA, but it ain't.

What is also amusing is that Mauser 98s have a Whitworth form (55 degree) breech thread and breech up at the end face of the tenon, just like a SMLE. Type 30 and 38 Arisakas are full of Imperial threads; Type 99s are completely metric, as near as I can tell. I suspect that there was a LOT of British tooling in German and Japanese arsenals at that time. Funnily enough, the Japanese ship building industry kept on with British threads through and well past WW2. You can find Admiralty, Whitworth and BA in their vessels.

ALL of the commercial aftermarket barrels I have seen for Mauser 98s seem to have 60 degree UN form threads and folks tend to breech them up against the front face of the receiver. I have never whacked a thread gauge into any of the post war / commercial 98s though.

Bruce on Oz, I'm always blown away by your knowledge on these technical matters. I was just looking through some of your old posts looking for some bit and pieces, all very interesting.

Threads are certainly a interesting subject. Over the years I have cut alot of threads, mainly on CNC machines, most of which were BSW, UNC, Metric, and pipe. Started off using die boxs in threading machines before CNC came along.
Thanks for the interesting info,
Rastis.