A source for British Whitworth threads in a 3/16" x 30 TPI screws?

[biometrics]

I know this is a bastard size that falls between the FINE and COARSE definitions, but it is the thread size for the grip retention screws on original German Luger pistols. 3/16" x 30 TPI Whitworth 55 degree threads.

The threaded shank is only THREE to FOUR threads long, so any length greater than 0.1 inch would work since I could grind them down.

I looked at McMaster and Fastenal, and couldn't find anything close.

Anyone know of a source for such screws? Just as important is a source for a tap to chase the threads with?

Thanks for your help in advance.


P.S. I also posted this request on the PM Board...

[oldstarfire]

On a German Luger, not likely to be any inch size thread. I suspect it is a 5mm thread with a 1mm pitch, altho 4.75mm MAY be a possible.
30tpi = .0333" 1mm =.0394"

[Al Messer]

That a Luger would have Metric threads sounds logical to me as well.

[BigBoy1]

There are many gun parts stores that would have the Luger grip screws. Why spend the time and effor to make them when they are available for $3.25 each plus shipping?

http://www.gunpartscorp.com/catalog/...spx?catid=3124

[biometrics]

There are many gun parts stores that would have the Luger grip screws. Why spend the time and effor to make them when they are available for $3.25 each plus shipping?

http://www.gunpartscorp.com/catalog/...spx?catid=3124

Thank you all for your prompt responses.

Thanks so much for the link to gunpartscorp.com I visit there often but these screws and many other parts are often out of stock at GPC even if the website doesn't say so.

$3.25 per screw is not an unreasonable price even with shipping, but it is my hope to obtain a box or boxes of these screws at "normal" screw prices so I can make them available to other collectors and enthusiasts at a much reduced price.

While the use of metric screws would seem the logical thing to assume... Even I was surprised to find out that the screws are English in origin.

As far as the requirement for British Whitworth screws instead of metric... it is believed that when the original manufacturer of the Luger pistol (DWM) tooled for production just before the beginning of the 20th century, that they used what was likely the most prevelant equipment for manufacture, including for the only two screws on the gun... the grip screws. Another theory is that they wanted the screws to be proprietary so owners would have to come back to the manufacturer to get replacements instead of going to the local hardware store in Germany and other places in Europe where metric screws would be found.

Machine tools from England enjoyed high popularity around the globe because of their reputation for accuracy and because the British Empire reached that far.

How do I know these things? Because I am one of the discussion board moderators at Lugerforum.com, a website for collectors of these pistols, and their accessories. I have also studied these pistols for the last 50+ years.

I have a complete set of digitized military P.08 Luger blueprints from 1913, and attached is an the extract of the line in the drawing specification table from the original print that contains the screws.



ALL other dimensions on these prints are in metric measurement notation. Only the screws are specified in English measurements. Despite being manufactured by half a dozen different manufacturers during its production life, once the gun had been officially accepted by the German and Swiss military (among many other nations), the screw specification never changed from the original prototype in 1898 until the end of official production and assembly after the end of World War 2.

...and so with all that said, if anyone knows of a source for screw fasteners with this thread spec, please let me know...either here in this post, or via private message.

And thanks again to all of you for being so helpful.

(BTW, if anyone wants a set of these digital P.08 blueprints, you can find them in the Classifieds at the above website...)

[RWO]

The original screw threads are so close to 10-32UN that if you run a tap thru the shallow little holes you probably won't remove anything but some metal dust. In fact if you were to put one of the after market screws on an optical comparator, I'm betting it would be 10-32 if there was enough there to measure accurately.

So, I say spend your time on something that makes a difference and make up some 10-32 screws out of drill rod unless you can find a hardware store screw that has a suitable head to reshape. That's what I did. The Luger gods will never know.

RWO

[RWO]

I didn't realize you needed them in quantity until I saw your post on PM Google is your friend. I guess you will have to find a shop to make them.

Tap http://www.tapsndies.com/catalog/ite...55/6851593.htm

Die http://www.tapsndies.com/catalog/ite...10/6865208.htm

RWO

[JCHannum]

Threads in use at the time the Luger was developed did not follow the standards in use today. In firearms as in many other items that have survived from those times, legacy threads are quite common. It is a matter of what was available and worked, nothing more.

10-30 taps and dies are available from Victor at a much more reasonable price than the previous source;

http://www.victornet.com/tools/Speci...-Taps/199.html

http://www.victornet.com/alphabetic/...quot-/210.html

You might check with them to see if a 3/16-30 is available.

Even if you were to find a source of screws in the proper thread, it is very doubtful that you would be able to duplicate the length and head profile. Your best bet is to find someone with a screw machine to make you a quantity.

[Toolguy]

Brownell's also has blank screws of various sizes that you can make whatever thread pitch you want.

[biometrics]

thanks again for all the responses... It looks like victornet is the source for the taps and dies... Now if I can find a hobbyist with a swiss screw machine... Hmmm...

-John