Lee enfield bolt fitting

[Enfield_Fan]

What's the proper procedure to fit a bolt to a Lee Enfield Rifle? I checked mine and only one of the lugs is making contact. Wondering how I should proceed.

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Information

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[tbonesmith]

Peter Laidler's list of on line articles is a sticky in this forum: Index of Peter Laidler's on-line series of articles.......
The article that will help you is: http://photos.imageevent.com/badgerd...0boltheads.pdf

Check out the rest of the articles and posts, it's GOLD!!

[jmoore]

Maybe this link will do right?:

http://photos.imageevent.com/badgerd...0boltheads.pdf

ETA: Yup! Click above!

[Enfield_Fan]

Lots of great information there. Are replacement bolts and bolt heads still available? Is it possible to stone to much material off the bolt and render it worthless? Or could you simply keep extending the bolt head within reason?

[tbonesmith]

Very possible to stone too much off. You don't have much room at all.

[Bruce_in_Oz]

If we are talking about a N01 Mk111 type, several things must be borne in mind:

1. There was ONE and only ONE bolt head issued for that rifle until a tiny batch of "longer" boltheads were made at Lithgow post WW2.
2. If the receiver and bolt have the same number and these numbers appear original, you have a problem.
3. SMLEs were made from a variety of carbon steels; no fancy alloys like 8620 etc. Thus, each component had its own peculiar heat treatment to echievr the desired hardness, malleability etc. Essentially, the locking surfaces are case hardened. If you have a chance, take a close look at a prime, unrefurbished specimen of late Lithgow production. There you should, see a small area of discolouration and surface texture change on the exterior of the receiver immediately to the rear of the locking shoulders. This "defect" is where the carbon electrodes were applied to "spot-heat" the metal around the thrust-bearing shoulder as part of the heat-treating regime.
The hard "skin" on SMLE receiver locking shoulders is quite thin; ditto the bolt lugs. If you lap off more than a couple of thousandths from a component that has already been cycled a few million times, you will probably have little hardness left for correct operation.
4. Without a "master bolt" or factory gauges, establishing the exact staus of the bolt and receiver is very difficult, especially if you also do not have all of the original documents for data.
5. If the suspect" shoulder is the one on the right hand side, the gap can be measued with feeler gauges after you close the acton with the striker cocked and preferably with a DUMMY round in the chamber. This condition provides a reasonable emulation of the alignment of the components immediately before firing. If it is the LHS shoulder/lug, good luck.
6. The one glimmer of hope is that on the "non-contact" lug, the error MAY be only just greater than the thickness of the film of bearing blue. The trick is to establish just how much greater.

[Enfield_Fan]

Bruce this is a NO4 MK1 i am dealing with. I need to put some blueing on and see what it looks like i have just been inking it up with a sharpie and seeing what gets scraped off may not be the most reliable method. I tried to get a .001 brass shim in the right side and could not get it in at all. I purchased this book The 2012 Complete Book on Lee Enfield Accurizing and have been going through some of the steps in it.

[Enfield_Fan]

Here is a picture of the channel the left lug rides in. Does this look normal? Not sure if it is supposed to be relieved like that at the top. Maybe to allow the bolt to close if you happened to get some crud in there? Also on closer inspection some of the ink rubbed off on the left side on the receiver but did not scrape any off on the bolt itself. Going to actually blue it tomorrow and see what it looks like. I think it may not be as bad as I thought. I went into a panic there for a minute thinking it may be beyond repair.

[Bruce_in_Oz]

Enfield Fan:

Some consoling things about No4s:

Most of them are newer than most SMLEs

You can still find the various different-length bolt heads around the place.

However, whilst most dimensions are different, in varying degrees of subtlety, most of the gauging principles and even tolerance schedules of the No1Mk111 apply to the No4.

The LHS locking shoulder (resisting surface) was rough-cut using a semi-ball-nose end-mill cutter. That is the tool that left all those swirly marks in the shoulder recess. The final forming of the critical locking surface was done with a shaving tool. This is essentially a long-ish bar, of hardened tool steel, with a tiny cutter blade attached. It resembles a boring bar with the cutter bit halfway down its length. There was a jig that guided the final shaving tool. There was also a set of special gauges to check the work at each stage.

The trick was to cut the load-bearing surface at the correct helix angle AND in the correct place. Important point: because Lee Enfield locking surfaces are HELICAL, as are those on P-14 and M-17 rifles, it may be a bit injudicious to just go in with a Dremel or diamond file and grind away. On the “plus” side, you only need a contact area, at lockup, of about 2mm square, to keep it all together.

One thing to note is the tolerances on the relative positions of the gauging points on bolts and receivers. The ABSOLUTE position of the bolt lugs has a tolerance of 0.004”. The allowable DIFFERENCE in relative location of the lugs is0.001”. “Cutting it fine, so to speak.

On the receiver, the allowance on the mean location of the gauging point on the shoulders is 0.004”; the tolerance on shoulder RELATIVITY is 0.002”

But wait, there’s more!! I don’t know about the No4 process, but with SMLEs, the piece d resistance, so to speak, was that the initial chamber in the almost-finished but un-fitted barrel, was cut a bit small. There was a “special” proof cartridge used to proof-fire the barrel in a fixture and then, if it passed, it was finish-reamed and subjected to more operations and gauging.then assembled to the “not quite finished” bolt and receiver. This assembly was then “proved” again with a cartridge containing 33grains of No3 Cordite and a service bullet of 215 grains. This proof firing also “set” the locking surfaces.

[Enfield_Fan]

Thank you lots of great information there!