Lithgow SMLE. How were the barrels rifled?

[BFMIN]

I ask because of this interesting close up shot.
Its about 1/3 of the way into the barrel from the chamber end & I only found it recently while using a bore-scope to check for cleaning of fouling.
3 parallel transverse grooves very evenly spaced with an attendant smaller transverse groove equally adjacent to them all. It does not repeat anywhere else in the bore. I'm guessing some kind of tool mark?

 

[Doco Overboard]

I would think thats a tool mark from deep hole drilling a forging that was not completely removed during the rifling and reaming operations.
I have text that describes the types of machines, tooling methods used used to produce SMLE barrels.
There were two used in England with alternate methods inter woven between the two to produce barrels at different times, locations.
Maybe Lithgow used a slightly differing process I couldn't say.
The pamphlet discusses home island techniques, machinery tool design proofing straitening, viewing etc. etc.
What I can say is that the new BSA, Indian and Lithgow barrels I have are finished with a 301 bore.
In order to use a chamber finisher for a few of them I need to have it ground so the pilot will enter the cone.
Pratt and Whitney provided capstan lathes to the English factory for a number of machining operations as well as of course English made machinery.
All the barrels were to be reamed then lapped to final dimension before completion. The grooves and lands or bore not at the same time either.
An amazing process and the most important for building a gun. Is the construction of the barrel.
Because of the deep hole drilling needed to start the process.
But to answer your question, the barrels were cut rifled in England for sure based on the text I have.

 

[BFMIN]

Thanks, very informative.
I'm guessing some kind of tool chatter maybe?
I know some were draw lapped after rifling ("D") stamped, but not if the Aussies did this?

 

[outrider58]

I would think thats a tool mark from deep hole drilling a forging that was not completely removed during the rifling and reaming operations.
I have text that describes the types of machines, tooling methods used used to produce SMLE barrels.
There were two used in England with alternate methods inter woven between the two to produce barrels at different times, locations.
Maybe Lithgow used a slightly differing process I couldn't say.
The pamphlet discusses home island techniques, machinery tool design proofing straitening, viewing etc. etc.
What I can say is that the new BSA, Indian and Lithgow barrels I have are finished with a 301 bore.
In order to use a chamber finisher for a few of them I need to have it ground so the pilot will enter the cone.
Pratt and Whitney provided capstan lathes to the English factory for a number of machining operations as well as of course English made machinery.
All the barrels were to be reamed then lapped to final dimension before completion. The grooves and lands or bore not at the same time either.
An amazing process and the most important for building a gun. Is the construction of the barrel.
Because of the deep hole drilling needed to start the process.
But to answer your question, the barrels were cut rifled in England for sure based on the text I have.

I came here to say only this part(bolded).

 

[BFMIN]

That's cool. Thanks again.

 

[eruby]

Hmmmmm

 

[TI-tick]

Hmmmmm


View attachment 434695

 

[eruby]

 

[TI-tick]

View attachment 434699

Sticks and stones may break my bones,
But eruby will never hurt me.

 

[TI-tick]

I ask because of this interesting close up shot.
Its about 1/3 of the way into the barrel from the chamber end & I only found it recently while using a bore-scope to check for cleaning of fouling.
3 parallel transverse grooves very evenly spaced with an attendant smaller transverse groove equally adjacent to them all. It does not repeat anywhere else in the bore. I'm guessing some kind of tool mark?

What kind of boresight? The detail is extreme.

 

[Doco Overboard]

When drilling the bore the shape of the bit is not like the point of a twist drill at all.
If you could picture an elliptical or D shaped point ground in a peculiar manner with the intent to keep the bit straight and on course is a particular challenge.
Also, the the material the barrel is made from also has has soft and hard spots in it that make it difficult to keep the bit on course because t has a tendency to walk.
The chips produced are dependent on the shape style of bit and emerge as wire, disc and ribbon if I remember as such.
What happens is the pressure and heat generated needs to have a large amount of coolant pushed through the bit the whole time the barrel is being turned. The barrels were turned onto the bit and not vice versa. Underneath the shop floor was a whole system designed to provide capture the coolant not unlike a modern sewer system that relied on gravity and is remarkable in its own right.
For rifling, there has always been discussion around number of grooves odd even etc. When the cutter is introduced to the bore there is one camp that believed if the cutter is supported by a land as it is rotated through he thats the better way vs an unsupported cutter in a barrel with an even number of grooves and so on.
The cutter also needs to sharpened and shimmed by a master mechanic whose only job was to work in the barrel shop and do the specific production actions for SMLE barrels made in England.
The information regarding rifling is from another treatise but germane to the conversation as well.
C, next time I see you Ill give you the book so you can check it out.

 

[BFMIN]

Thanks again for the detailed post.
We seem to be recovering from our major issues & getting back into life.
We made it to Marshyhope for the first time last weekend, Val & I will try to make it there for next Sat round about 1:30.

 

[BFMIN]

What kind of boresight? The detail is extreme.

Its the basic Teslong "flexible" USB model.
Do get the "set of 5 mirrors in different diameters" though. They'e pretty much essential for any bore over .22

 

[Clovis]

I ask because of this interesting close up shot.
Its about 1/3 of the way into the barrel from the chamber end & I only found it recently while using a bore-scope to check for cleaning of fouling.
3 parallel transverse grooves very evenly spaced with an attendant smaller transverse groove equally adjacent to them all. It does not repeat anywhere else in the bore. I'm guessing some kind of tool mark?

I don't want to assume but I would guess from seeing some of your posts you may own more than one Lee. If that is correct ( and apologies if it is in error) I would be curious if you examined others if the same tool marks existed in them as well.

 

[Doco Overboard]

Thanks again for the detailed post.
We seem to be recovering from our major issues & getting back into life.
We made it to Marshyhope for the first time last weekend, Val & I will try to make it there for next Sat round about 1:30.

Ill see you there.
I need your input for a few sighting projects I have left unfinished for best way to accomplish a final effort.
Also we have to get a plan squared away for the morris tube rifles.
Ive been holding parts for some time and want to make good for the F/s arrangements we planned some time ago.
Im glad to hear you and Val are doing well.

 

[BFMIN]

Absolutely I'm sorry this has taken so long with it extended hiatus.
I'll bring everything I have & we'll get it sorted for parts at least!

 

[BFMIN]

Yes I have a bunch of them
A '55Faz No4 Mk2
A '43 Savage No4 Mk1*
A '14 No1 MklIII* BSA
A 43 BSA No1 Mk5
None of them has anything like this in them. Just the Lithy SMLE.

 

[Clovis]

Yes I have a bunch of them
A '55Faz No4 Mk2
A '43 Savage No4 Mk1*
A '14 No1 MklIII* BSA
A 43 BSA No1 Mk5
None of them has anything like this in them. Just the Lithy SMLE.

I thought you likely had more than one...but as to the Lithgow having the tool marks I suspect it may be a one off or just several barrels made that day or week by the same worker likely working several extra hours a day or extra days a week because they had to get the rifles out to the troops because of the war. I've got a Lithgow but I can't recall the year, if I dig it out I'll post it.

 

[Doco Overboard]

Just a quick update fromsome reading last night.
During the drilling / reamering process defects would obviously occur from the machine operations.
The types of tool marks were understood and then a process known as setting in would occur.
It’s important to also know that a third defect resulting from proofing was an anomaly with SMLE barrels subjected to first proof before they were final reamed and rifled The defect was known as a powder swell and the proof charge was abnormally higher than later proof loads.
What would happen then is during viewing, the defect would be located by a skilled workman and then be “set in”by hammering out the tube effectively raising the defect internally so that final reaming would remove the circular marks as the bore was brought to its final size.
Reamer and drilling operations produced both semi and completely circular marks with if I’m remembering correctly reamer marks only affecting a portion of the bore due to the nature of the design of the tool and how it was applied.
A barrel had to be ready to “make” before other numerous operations were undertaken to produce a final product that resembles what we take for granted in final appearance.

 

[BFMIN]

I never knew that, thanks.