Enfield barrel threads

[Lord Eoin MacKenzie]

Are the threads on a Mark 4  barrel the same as a Mark III?   I found a like new barrel with part of the receiver attached in the misc gun parts in my shop.   I also have a BUBBAED Mk III.

[Drydock]

I believe they are the same.

[Niederlander]

I believe you're right, Chuck.  I read somewhere that it's the same as a common British pipe thread.  Go figure!

[Guns Garrett]

The barrel thread on the SMLE (all Marks) is the same: .997' major diameter, 14 threads per inch, "V" type (assume 60 degrees?).  Whitworth (55 degrees) thread NOT specified.  NOT tapered, so is NOT pipe thread.

Thread shank is .6875" long, with a .900" dia. portion .100" long at the chamber end unthreaded.  No mention if the shank length is the same for all marks.

Extractor cut at approx. between 2-3 o'clock position (viewed from receiver end)

Reference: "Gunsmithing" by Roy Dunlap (1950). 

[eljay]

i assume you are talking about a no.1 mk 111, and a no 4 enfield, if so, it will screw straight in, the only thing you will need to do is recut the extractor slot as they index differently, fit a rear sight, and possibly open up the barrel channel as i think the no. 4 barrel is a little thicker.

[Sir Charles deMouton-Black]

Years ago, one of my military weapons techs fitted a No.4 barrel to a Martini action. It was threaded the same but required a headspace washer to avoid having to re-chamber.  I see on an Enfield forum that others have done similar things and called it a SMLEtini or something similar.



Ref; Single Shot Rifles and Actions 1969, Frank De Haas & Gun Digest Books.
Barrel specs. MARTINI ENFIELD .303
Reinforce 1.18" dia.  (Slightly oval, 1.025 side to side. and flat on top & bottom.)
thread dia.  1.00 (Only three thou' different than the MKiii or No.4)
length of threaded area .70 (SMLE is .6875 - diff. 0.0125)
Thread description   14V T.P.I.  (De Haas does not mention the thread angle.)