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Discussion Starter #1
I recently acquired an M1871/88 Dutch Beaumont-Vitali with an incorrect machine screw on bolt that attaches the bolt head. Is it Whitworth threads? If so, are modern Whitworth threads (e.g. motorcycle parts) the same?

I'm also looking for the insert on the right side of the bolt head, opposite of the extractor. This may become a Khyber Pass project.

This rifle is an unique piece of firearm history.
TIA
Bill
 

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They almost certainly aren't Whitworth unless the Dutch government bought machines from Greenwood & Batley or another English manufacturer. The best idea is to find a thread gauge and measure them. I don't know what they are but I would not be surprised to find they were American 60 degree threads since, at the time the Beaumont was made, Pratt & Whitney was supplying the lion's share of gunmaking machines to all of the European powers. The Spandau, Erfurt & Danzig arsenals were all euipped with US built machines.
I have a Beaumont in the office and, if I remember, I'll check it tomorrow.

Joe Puleo
 

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Dutch Beaumont threads.

Firstly, the Dutch Government did NOT make the Beaumont rifles...they were made by a private contractor named J.Stevens, of Masstricht.

The English name suggests a transplanted Gunmaker from the Old Dart, and would have probably used Britsh-made or British-Supplied machinery in the 1870s-80s (G&B or even P&W (USA)). Threads would have been most likely Withworth Form, if not a specific standard series.

The 1870s to 1890s was a very fluid time for "Gun threads" with a mixture of English, US, and Metric systems in use, along with more traditional "Horological" and "Lockmakers" threads also in use, according to custom and usage, in different gunmaking areas (ie, each was standardised witin an area of supply, but not interchangeable between areas.

ON top of that, the US Sellars(Later SAE and UNC/UNF) thread system, first proposed in early 1860s, was based on the Springfield Armory version of the French 1792 Metric system of Gun-threads ( converted to "inches" and TPI" for US use, but with 60 degree threads, rather than the English 55 degree system.)
Mauser of course, working on his first prototypes in Belgium (1867-69), chose a crossed Withworth and metric system for his gun threads, hence the 1/4x22TPI main screws, and yet metric screws for the other bits. What was available at the time, I suppose. The 22 tpi is not standard to any other "Standardised" screw system.( 1/4 x 20, 1/4 x 24 , 1/4 x 26, 27 and 28 are all found in "Standard" or Brass thread systems, but not 22.)
The same is found with the Enfield 1/4x30 used on P14 and M17 screws...not a normal pitch found on any off-the-shelf screwing machine.


Getting back to your Beaumont screwed part.

Don't "assume" what it might be...measure it first (Diameter and thread Pitch, using both Imperial and metric calipers(I have a double dial type, which gives both sideby side) and then a multiple thread system pitch gauge "teeth" to find the correct pch...and remember that many "metric" fine pitches approximate both US and Withwork pitches... by holding the gauge and scrw up to the Light, or observing under a magnification Loupe, one can tell whether the match is "close" or "exact".
On a lot of short thread runs, the differance may be inconsequential, but on important or long thread, the differences can be substantial over a relative distance.

One is often surpirsed with the resluts, which are "not" what one might have "assumed" from the natioanl origin of the firearm.

Example...Berdan II and Mosin Nagant rifles are all Withworth screw threads (machinery by G&B) even to the Chinese made T53 of the 1960s (made on Russian machinery).

Werndl rifles were made on Pratt & Whitney machinery, and the threads are early Sellars UNF type...

Enfield made rifles have a thread system called the "Enfield Inch", and have some tolerance problems with SMLEs made to the P&W "Imperial Inch " standards. Rifles No4 use BSF type threads, and are Industry standard.
German rifles used Metric threads for everything EXCEPT the Main Locking screws and the cross stock recoil bolt, which was 1/4x22 Imperial (" 6,35mm x 22 r. pro Zoll, Englischer")

And the Japanese, used a variation of the US Sellars system on the Type 38 (metricated) and pure metric on the Type 99; The Japanese export Siamese Type 66 Arisaka used a purely US type thread and metal measurement system (in fractions of Inches, up to 1/128")

Regards, Doc AV
AV Ballistics.
 

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Discussion Starter #4 (Edited)
JV Puleo and DocAV,
Thanks for the replies. I forgot about the rolling block machinery; just not really knowledgable on BP rifles. Yes, it was made by P. Stevens of Maastricht.
Unfortunately, I do not have the screw so maybe JV can provide a measurement. I'll measure the present loose screw, albeit what I may think it to be, and check my misc. bolt collection for other hand fits.
Thanks,
Bill
 

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Here are your dimensions:
Overall length: .556
Head Dia.: .362
Head thickness: .205
Major Diameter of thread: .227
TPI: 24
Length of threaded portion: .357 with the last .135 turned down to the minor dia. or slightly smaller (I forgot to measure that one)

Doc AV is right about the thread profile, it appears to be British, i.e. 55% with rounded roots and crests although my middle-age eyesight and the small size of the screw, combined with my antique thread gage leave some room for question here.
The head has a very shallow dome...a "panhead" I believe!

This is very close to the measurements for 1/4" BSF which, unfortunately has 26 TPI. Athough, because it only engages about five or six threads 1/4 BSF might work. I'd try it, but not too agressively. You don't want to damage the internal thread or break off the screw. I believe the Beaumont long pre-dates the development of BSF threads so that shouldn't be surprising. It shouldn't be a difficult thing to make for someone with an appropriate bench lathe but I very much doubt you'll ever see one for sale unless it came from a Beaumont.

Good luck,

JV Puleo
 
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