Action screws

What thread is on 98 action screws??
Is it Mausers own??? as I suspect

It’s actually a UK standard size, not metric. Can’t recall the exact thread pitch.


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WD 40 effects

I allso thought it was an Imperial thread 25TPI????

Just measured a couple. Body diameter is nominally .25". Measured one at .254". Thread pitch is 22TPI. I did a quick search and found that the thread is a British Whitworth form - 55 degree angle between threads. US Standard is 60 degrees.

So to take this further down the rabbit hole..... I got curious and measured mounting screws from a sample of my German pre-98 series rifles - 71, 71-84, 88. All three models use the same .25" diameter and 22 TPI thread pitch. Lengths, thread lengths and head diameters vary. My pre-Gebr. Mauser, Royal Oberndorf Arsenal Dreyse needle gun uses the same .25" diameter but the thread is about 20TPI.