The exact pitch and diameter have been mentioned in older threads. I think it was 26 threads per inch. the biggest problem will be duplicating the thread form. The thread form with the large radius on the roots and crests would require a custom grind. if only one or 2 taps are being made at a time it they will cost several hundred dollars to make.
Making custom screws with the standard 8-32 thread and custom heads to resemble original Krag would be an easier solution as long as you do not get them mixed up.
If I made a set for my own rifle it might take 1/2 a day. Making several hundred for someone selling them would be close to $5.00 each. So the amount mentioned in the other thread $6.00 to $8.00 dollars is very reasonable if they are hardened and nicely finished.

BR is correct, I just pulled and measured the front sight screw from my grandfather's original Krag and it does measure .156 diameter and 30 threads per inch more or less. The imperfect dies they used back then produced "drunken" thread pitches.



I think I just attached an image. If so it is that screw on an optical comparator. I measured about .101 inches across 3 threads, should be .1 if the threads were exactly 30tpi.
An 8-32 screw's theoretical OD is .166, because the threads have tiny flats on the peak even the best quality screws will mike a few thousands smaller.
Measuring with thread pitch diameter wires, I got this
8-32 over wires .1875
.156-30 over wires .1865
Even though there is a large difference in ODs the large radius on the crest of the Krag screw means its theoretical OD is larger than measured. I just checked to see if a krag screw would fit in a precision 8-32 hole and the answer is no. The rounded roots get in the way. It would be very bubba to force it, but it would have been amazingly close.

butlersrangers wrote on Mar 12^th, 2019 at 3:07am:

Hello BR, this is not the thread I was thinking but it does have the measurements I took of my dad's Krag sight screw. So it is even better. Thanks!
Hope you get over the irritation soon, otherwise you will be missed greatly.
I tried searching from Yahoo using " Krag collectors association forum  butlersrangers and screw sizes" did not turn up this thread or the target thread.
Using google  and the same type search found this one and a number of others. Those threads are still there just searching with a more powerful means is necessary.
I should have a list of especially useful threads for KCA, I have one with some threads for Practical Machinist. You have been so good at finding them for others, I thought you had total recall or a list. Maybe you and the administrators can start a thread for important references in the "Older Threads" section, that way it will always stay near the top.

I checked with our web guy and he assures me that nothing has been deleted by us. The web site was compromised once in the early years and some very early posts were lost but this was long ago. I did find that the default setting for replies was 100 so I had it raised to 500 which should help. I also did some searches and found the same posts and a few others depending on specific wording. They are there but some times the wording in the posts affects the search.
Again all post are there to the best of our knowledge

Boy, am I glad you did not go away.
I learned about that using the external engines over at Practical Machinist. The forums are using software that just is not that good for finding internal stuff. Maybe if you know the exact wording and spelling used in the thread. Yahoo and google are not set to look for alternative mechanical terms. I like yahoo's keeping several tabs open better than google, but sometimes google finds more stuff.