British Gunmakers screw threads

Hi Dave,

In the days when most guns were hand made, most individual gunmakers had their own threads. Male threads were struck by hand in the lathe, and they made their own taps. As a consequence, on very old guns you will find some really weird threads! Not very helpful to you, I'm afraid! - Mike George, Technical Editor, Sporting Gun Magazine

The thread for bicycles I believe were set up as a standard first by BSA most of the threads being 26TPI,This then got accepted by CEI (cycle engineers Industry)which evolved into the British standard for cycles BSC.

Most of the threads except for Headsets and bottom brackets which used the 24 TPI range and the 9/16" X 20 tpi which is the grenral pedal thread.

Strangely enough the Italian Campagnolo enlarged the wheel spindle threads from 5/16"(8.00mm)X26TPI to 9mm and the Back spindle thread from 3/8"(9.5mm) to 10mm so that is why you get metric outside diameter with a british Teeth Per Inch (TPI)

Regards

John

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I can tell you that the small sound moderators are all UNF 1/2 x 20, be it manufactured by Parker hale, Sako etc, etc. - It's kind of an unofficial industry standard.

Nick

And a good number of centre fire moderator threads are 5/8" UNF.

graham.

Yes I agree.

Both my 22/250 and the 25-06 are so. But they are heavier barreled versions. A 'standard' weight barrel at 5/8" may leave not a lot of shoulder for the face of the moderator to mount to.

Nick

Hi all,

Since posting my first request re gun makers screw threads, a good friend provided me with the following site

**LINK**

This lists the threads used on nearly all of the British military rifles made by BSA at Enfield. For those of you that have an interest in such things, the list makes interesting reading. It screams of trade protection, at least up until WWII when the gun makers began using the BA thread system. The older screws were very odd diameters. Likewise the thread pitches are certainly interesting and some would be a challenge to cut. I would assume that BSA made most of their own tooling, as I recently acquired several profile milling cutters with BSA marked as the maker.

Dave, Very interesting post, I see a lot of the 26 1/3 TPI which is still used on most gun cleaning rods

Stuart

The term gunsmith thread derives back from the days when there was no industry standard.

When any thread was made it was by either that individual or company and liable to change with those subsequent parts, hence the term gunsmith thread meaning it could be anything. Many a time had to make a die to cut a male tap so that original female thread either cleaned up or deepened with extra thread. Some of the threads can be really crude as in filed in by eye forming a female thread in the part.

Quality manufacturers today still use a mix of BA, UNF and BSF.

Barrel threading unless specified is usually done a UNF pitch, though an ever increasing 1mm pitch is available good enough for .338 Lap with spigot behind.

I have tried posting a table of gearings for Myford ML7 lathes with gearbox to cut these odd threads, but it was too long to post in one piece and I thought it would lose impact by being broken up.

If anyone would like a copy please send me a message with your email address.

Regards Brian

Hi Brian,

Thanks for the offer, yes I would like a copy, as it saves me working them all out each time I need one. My address is *@*.

Thanks again.

Dave

Moderator's advice: Please use PM's to exchange email addresses.

Edited By Neil Wyatt on 08/05/2014 10:00:41

Hello Dave,

I tried to send them but your email address couldn't be found; I did a 'copy and paste' of it so the fault is not one of incorrect transcribing, so please check it.

Regards Brian

Hi Brian,

What I sent is correct! If you would be kind enough to post your address, I'll try the reverse.

Sorry about the glitch.

Cheers

Dave

Hello Dave,

My computer didn't recognise it for some reason. We'll try the reverse coupling---

[email protected]

Regards Brian