Long Branch 2 and 5 groove barrels

[x westie]

I find the Lee Enfield Rifles a fascinating subject..especially the Long Branch models...but i have to admit ..though i read as much as i can about these rifles....and read the posts on , i still have a lot to learn.....there are lots of well informed MilSurp who i can tell a very well informed on the Long Branch rifles....my question is...i have 2 LB rifles....a 1942 with a 2 groove barrel...and a 1943 with {i think} is a 5 groove barrel....would there have been several barrel making machines at the LB..factory??...some machines turning out 2 groove barrels,..while others turned 5 groove barrels..

I wish there was more info on the Long Branch factory....would make a great book...

Information

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[stencollector]

I think the change to 2 groove was simply to save on the cutters required on the broach, and may not have otherwise required any real change in machinery. It was an accepted change by the British to make manufacture easier, since it did not result in a unnaceptable change in accuracy.
There was a change in the 50s at Long Branch over to using surplus Inglis Bren equipment which resulted in 6 groove right hand twist barrels.

[tiriaq]

Were LB barrels broached, or cut rifled using Pratt & Whitney type sine bar riflers?
If barrels were broached, only the actual cutting tooling would need to be changed. If a cut rifler were being used, there would be more work involved in resetting the machine, althought the same cutter would work for 2 or 5 groove.
The time required to broach 2 or 5 groove barrels would be the same. One pass, that's it. Whether there would be much savings in the tool room making 2 groove versus 5 broove proaches, I would not know. Using a sine bar rifler, a 2 groove barrel would require 40% of the machine time of a 5 groove barrel.
I would doubt that 2 and 5 groove barrels would have been produced simultaneously, although there could have been a transition period when tooling was phased in and out.

[Lee Enfield]

I have seen Long Branch's with 5groove bbls dated 1941, '42, '43, '44, '45, '49, '50, '51

The earliest 2 groove barrel I've seen is dated '42. I can confirm '42, '43, and '44. I have heard of a 1950 dated 2 groove barrel.

I do not recall seeing a '45 dated 2 groove LB.

The earliest 6 groove Mk4 barrel I have is dated '48 IIRC (will confirm). It's on a 1949.

The latest 6 groove Mk4 barrel I have is dated '58.

Having said that, I understand that the knox form dates are not production dates, but are breeching dates.

Does anyone have an UN-DATED Long Branch barrel??

[Lee Enfield]

Were LB barrels broached, or cut rifled using Pratt & Whitney type sine bar riflers?
If barrels were broached, only the actual cutting tooling would need to be changed. If a cut rifler were being used, there would be more work involved in resetting the machine, althought the same cutter would work for 2 or 5 groove.
The time required to broach 2 or 5 groove barrels would be the same. One pass, that's it. Whether there would be much savings in the tool room making 2 groove versus 5 broove proaches, I would not know. Using a sine bar rifler, a 2 groove barrel would require 40% of the machine time of a 5 groove barrel.
I would doubt that 2 and 5 groove barrels would have been produced simultaneously, although there could have been a transition period when tooling was phased in and out.

Wheaty has some broaches with multiple cutters...

[tiriaq]

Wheaty has some broaches with multiple cutters...

ALL broaches have multiple cutters. A broach is passed through the barrel only once. A broach can be made to cut any number of grooves desired. How does broaching a 2 groove barrel save time or money compared to broaching a 5 groove barrel?

[stoggie]

Were Enfield barrels buttoned or broached? Explained:

Lilja Precision Rifle Barrels - Articles: The Making of a Rifle Barrel

If they were buttoned, they would have been run twice for 2 groove, and 5 times for 5 groove. Therefore a 2 groove barrel would save time and tool wear by 60%, as noted by Tiriaq.

If they were broached, they would not save time, but they would save on cutting heads, as noted by StenCollector above.

[tiriaq]

Button rifling did appear during WW2, although I have never seen any suggestion that SAL used the process. Remington (Mike Walker) pioneered it, it was also used in Germany.
All grooves are formed in one pass when a barrel is button rifled. Its not 2 passes for 2 grooves, 5 passes for 5 grooves. The grooves are created by displacing the metal.
All grooves are cut in one pass when a broach is passed through a barrel. A broach is a long cutting tool, with a series of cutters to cut each groove, each cutter being slightly higher than the previous one. The broach is made from a single piece of steel. Making a 2 groove broach would be faster than making one to cut more grooves, but the time taken to rifle the barrel would be the same. A broach can be used to rifle a number of barrels before needing sharpening, reworking or replacement.
When a barrel is rifled by either button or broach, the actual time required to pass the tool through the barrel is seconds.
If a barrel is rifled with a sine bar rifler, of the Pratt&Whitney pattern, each groove requires a series of passes to be made, a fine cut being taken with each pass. It takes several minutes to cut rifle a barrel. If 2 grooves are being cut instead of 5, the number of passes and therefore the machine time is reduced by 60%.

[stencollector]

I must say this is turning into a very informative thread.

[x westie]

I think the change to 2 groove was simply to save on the cutters required on the broach, and may not have otherwise required any real change in machinery. It was an accepted change by the British to make manufacture easier, since it did not result in a unnaceptable change in accuracy.
There was a change in the 50s at Long Branch over to using surplus Inglis Bren equipment which resulted in 6 groove right hand twist barrels.

I have 1950 C No.4 Rifle with a 6 groove barrel,....it has been bedded and has a PH 5c sight......Thanks for your interesting post,....