Lithgow Lee Enfield threads

[6878mm]

Does anybody know what thread was used in Lithgow manuf. rifles
It will be some sort if imperial thread, I am guessing a unified thread??

[Blr243]

Barrel to action thread. Muzzle thread Cotton thread or other ?

[bladeracer]

Does anybody know what thread was used in Lithgow manuf. rifles
It will be some sort if imperial thread, I am guessing a unified thread??

I don't have a barrel to measure. Tom at T-Bone should be able to tell you for sure though.
According to Frank DeHass:

[No1Mk3]

Unified thread form is not British, it is American. Even though Lithgow used US made machinery (from Pratt & Whitney) it was set up to make parts using the British Standard Inch whereas all parts from the UK were made using the Enfield Inch which caused some problems with interchangeability which were soon fixed. To find a specific screw diameter and pitch you should buy Ian Skennerton's Small Arms Identification Series #23, about $15 now I think, as many tthreads are not a standard form, such as the bolt head which is 0.4175 dia x 20 tpi at 75 to 78 degrees flank angle, Enfield Form.

[No1Mk3]

That drawing bladeracer provided from De Haas also does not show that the thread form is also an Enfield Special which is 49 degrees 40 minutes.

[straightshooter]

Thread standards did not become truly established until the late 1800's and early 1900's.
The No.1 used thread forms unique to, surprise surprise, the Enfield factory. This can cause a problem when a standard thread is not a good fit or in reproducing small fasteners for models such as these when the original is lost or damaged or unprocurable.
This is not a major problem with machining a barrel tenon as slight variations in form are compensated for by machining and test fitting to a 'neat' fit.
The No.4 used mostly a BA thread form even when made in the US.