U.S. Krag screw threads???

[butlersrangers]

A recent forum question had me measuring Krag side plate screw threads with a thread gauge. While I was doing this, I began checking 'threads per inch' (TPI) and Major Thread Diameter of other Krag screws. The side-plate screw, rear barrel band/sling swivel screw, front barrel band/bayonet lug screw, and front stacking swivel screw all seem to be 26 TPI with Major Diameter averaging .180 inches. Strangely, 10 rear sight screws of 1896, 1901, & 1902 styles appear to be 28 TPI (I had expected 26 TPI). The Major Diameter of the sight screw threads varied from .158 to .160 inches. The trigger guard screws were 24 TPI with Major Thread Diameter of .245 to .248 inches. The trigger guard screws, front barrel band, and rear barrel band/swivel screws of the Krag were carried over to the 1903 Springfield, I believe. I am left wondering the influence and reason for the peculiar threads found on the Krag. Were these threads used on earlier Springfield Arms? Are they European and present on the Norwegian trial rifles? Are they influenced by British or Bicycle threads? I am curious.

[Century2]

I've seen it discussed many times with no real resolution?

Here was a go at it years ago...

http://www.jouster.com/forums/archive/index.php?t-12577.html

[butlersrangers]

Century2: Thanks for the jouster link on Krag Threads. It looks like 5MadFarmers provided a good reference with the 1902 inventory of Frankford Arsenal tap & die sets. (The .156 x 30 is probable for actual size of Krag sight screws and the .187 x 26 for side plate, and barrel band screws).

[Parashooter]

Here's a fairly easy way to count non-standard threads using just a camera and a computer. Example shows Krag rear sight screw.

[butlersrangers]

Parashooter: That is very handsome and clever camera & computer work. I was mainly curious why the U.S. Krag has such peculiar threads. This seems to be an intriguing story. I am sure some of the parts have been noted.