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No1 Mark 111 Breaching up
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01-27-2012 01:57 AM
# ADS
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No4's breech up on the shoulder, unlike the No1 which as you say, breech up on the face of the tennon.
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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.
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I doubt you'll get them tightening up with underturn, I have never heard of anyone needing to do this.
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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
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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.
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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.
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Thank You to Bruce_in_Oz For This Useful Post:
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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".
Last edited by Bruce_in_Oz; 01-30-2012 at 02:46 AM.
Reason: typo
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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.