Help with screw diameter and pitch for M1904 Vergueiro rifle

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jdac

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Good evening,

I'm hoping someone can help me with information about the pitch and diameter of the front screw holding the rear ramp sight on an M1904 Portuguese Mauser Vergueiro. Just got the rifle and the screw is stripped (actually was rolling around the box when I picked it up from the Post Office).

Putting my metric pitch gauge on what's left of the thread root, it appears to be close to 0.60mm pitch. When I try my imperial pitch gauge, it seems close to 42tpi.

I can't tell what the diameter of that screw was originally since the threads are almost gone. Measuring the diameter of the hole in the front of the sight where the screw threads in, I get 2.5mm.

Thanks in advance for any insight.

Joe.
 
On the Mauser-Vergueiro rifle, only the Action is Vergueiro.

Rest of the rifle was out-of-the-box Mauser parts.

Try a screw from a '98 or similar.
 
smellie said:
On the Mauser-Vergueiro rifle, only the Action is Vergueiro.

Rest of the rifle was out-of-the-box Mauser parts.

Try a screw from a '98 or similar.
Click to expand...

This X2.

OP, if the threads on the screw is pooched you can bet the threads on the base are stripped as well. You might be able to put in something like Devcon Steel Putty to fill the threads in the base and just pick up a replacement screw for the stripped one. Your will also have to rethread that base hole appropriately. The Steel putty needs to cure for a few hours to drill and tap properly but if you mix in some iron filings it will take on the same blue hue as the metal around it. It will only have about 60% of the strength of the original but that is still more than enough to do the job required of it.
 
So are we talking about the little screw sitting outside the wood stock at the front of the rear sight? To me it looks like this screw just helps secure the wood hand guard. On my 39 model, diameter of this screw is 0.1230'

How does one measure thread pitch?
 
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Thread gauges
 
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Thank you Diopter (and everyone)! That is exactly the screw I needed dimensions for. For the screw, I'll see about finding one from a Mauser 98. With the screw dimensions I'll also look for a tap to chase the threads in the sight sleeve.

Am I correct that the screw just locates the sight by slipping its point into a shallow hole in the top of the barrel and that the sight sleeve is actually then soldered to the barrel?

From what I've read, this is how the Mauser 98s are set up. If that's the case, then I don't need to worry about how much force the screw will see on recoil since it will be negligible or even none.

Thank you everyone!!!

Joe.
 
I don't think that screw has any function whatsoever once the rear sight sleeve is soldered in place. It certainly locates the sight initially, but once the solder is holding, I don't believe it actually holds anything.
 
Thanks for the further insights. Knowing the screw is really only used to position the rear sight for soldering is quite a relief since even if its not there at this point, function won't be affected.

Given the diameter and pitch of the screw and when and where the rifle was built, I suspect it's actually a 5BA (British Association) thread:

  • Outside diameter of thread: 0.126" (3.2mm) - although this is very slightly smaller than your measurement of 3.25mm, Diopter.
  • TPI: 43 (0.59mm pitch) - this is less than 0.0004" from your measurement Diopter.

Again, thanks to everyone who has helped me to get to a solution for my striped screw problem! I'm going to check with with Western Gun Parts in west Edmonton next week to see what they might have in the back for Mauser sight screws.

Joe.
 
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Most of the old Mauser rifles did not have metric threads but still used BSW,British standard Whitworth,but to complicate matters they did not use the standard pitch but chose an oddball one so you could not go to the hardware store and buy a standard screw or bolt.
In this case I would believe the screw would be 1/8,which is approx.3.25 mm,and there never was 3.25 in metric thread,so it must be Whitworth,a thread gauge will tell you the threads per inch(TPI),hopefully its a standard pitch.
Failing that you could find a metric 3.5 mm screw and retap the hole.
 
A lot of the old gun screws are GUNMAKERS' THREAD, which is extra-fine. Taps and dies are availabl;e for nearly all of them, but you aren't going to find them at Home Hardware.

Try Brownell's or else order through your local machinists' supply.

On some of them, sticker shock can be almost fatal! Be prepared!
 
Looks very much like the screw from a VZ-24 rear sight.One might work.If the threads are stripped in the sight base Loctite Form-a-thread would take care of the problem.
 
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