Krag stacking swivel screw size/thread

Recently bought a Krag rifle (1901 DOB) that lacked a stacking swivel. Bought one from a fellow 'MILSURPS' member with a screw. Screw I received fine, outer edge of upper band where it attaches has some thread issues that won't allow screw to turn in all the way. Anyone know what size and thread pitch is. Appears to be a #10 screw (?) with a thread pitch somewhere between 32 and 24 tpi. None of the screw checkers I have seem to have right pitch to measure. Need to clean up threads on upper band.

Do you think the threads would clean up with a needle file? I have a few pretty fine ones that may work for you. Wouldn't mind at all sending you a few, on me.

rcathey- Thanks for the offer. I have several good sets/grades of needle files, but the threads that need some TLC are just inside of the threaded hole on the outside of the upper band. I can screw the screw just within about 3-4 threads from being seated. I don't want to force it and strip what is there. If I had the right tap it would be a breeze. I have a number of gun screw size taps and dies, but the size I need isn't in my collection of course. Appears to be a size 10 screw with threads finer than 24 tpi and courser than 32. Don't have any taps that size. Do have a gunsmith not to far away who is a whiz on military and older firearms I can take to him if push comes to shove. I did read somewhere that the author made mention that the Krag rifles used some unusual thread pitches, don't know how true, but possible I guess.

DJ, I believe they are 26 TPI. Do a google search on the Krag Collectors Forum. They have some info on this. It might be real hard to find a tap that size. Salt Flat

Looked through the Krag Collectors Forum and found several threads and posts about thread sizes on Krags and the stacking swivel screw. One post advised most Krag screws are either 26, 28, or 30 tpi depending on the location. This could possibly confirm what I read somewhere else that the Krag is a firearm with 'different' thread pitches. Anyway the stacking swivel screw is supposed to be a 0.187 shaft diameter which according to a chart I viewed would be a #10 screw (comparable to what I checked), with a thread of 26 tpi. My thread pitch tool showed that 24 tpi was to course and the next leaf was 27 tpi which was to fine. A 26 tpi probably would be right on. No such tap or die in my collection. Will have to consult with my gunsmith source. Curious. Thanks for the lead Salt Flat.

What about getting a spare screw, cutting a groove down it lengthwise, and running that through a few times? For minor thread boogers, this’ll usually work.

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Originally Posted by rcathey

What about getting a spare screw, cutting a groove down it lengthwise, and running that through a few times? For minor thread boogers, this’ll usually work.

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I'll keep it in mind, good suggestion-never have gone that route, I've used a harder steel screw to clean up threads in a softer steel though(sort of the same principle as a tap). The gunsmith I mentioned earlier is a old time 'smith' who loves 'older' guns. If he can't find a part, he can make one, never have heard of anything that stumps him. I'm wondering if these 'oddball' thread sizes are just unique to the Krag or other guns of that era. Have never heard otherwise. I have other military rifles form the WW1/2, Korea, but have never had to seek or repair any screws/threads for them, just always used what they came with. Wonder what the Trapdoor used? I have dealt with percussion revolvers of the 1800's, but they're of the reproduction lot. Just bought a 03 Springfield not long ago, the next in line so to speak of the US Military issue, I have no idea if the military continued with these thread pitches with them or not. From what I've read some of the same parts or style used on the Krag were inherited by the 03. Did read a short bit some time back when the article mentioned the odd thread sizes of the Krag that they inherited some European traits in that respect being they were designed by Norwegian designers. Wouldn't think the US at the Springfield Armory would have continued the use over using whatever was more common in the US. "Above my pay grade"! Be something to read up on. I've read a lot on military firearms, but thread pitch is something I've rarely seen, always give screw diameter, length, head size, how much of the end was threaded, but rarely thread pitch-at least in the sources I've read. The journey continues.

The thread standard in use at the time the Krag was manufactured was United States Standard (USS).
This is an obsolete standard that is quite different from SAE and metric threads in use today.
I would contact S&S in NY. They are reproducing screws in this thread pitch, or have originals for sale.
United States Standard thread - Wikipedia

Product Detail

A reproduction screw would be a good choice for the idea I shared above.

I have been guilty of posting my observations, measurements, and suspicions about the origin of U.S. Arsenal screws and threads, on the KCA Forum.

(My WAG is that the threads may have been influenced by the French Military Arms we first copied at our Manufactories. I would be delighted if a knowledgeable machinist/engineer/researcher could throw more light on the subject).

In regard to the Krag 'Stacking-Swivel Screw', the thread size is approximately .187" X 26 TPI.

The same thread size is also used for the Barrel-Band Screw and the magazine side-plate screw. This thread size is also used on 1903 Springfield Swivel-Screws.

IMHO - A number of things happen to interfere with a good fit and caused damage to threads.
1. Wrong screw - wrong length. (A lot of Springfield screws were similar and had the same thread, but, the various screws were specific to their function and had differences. Over the years, the wrong screws sometimes got used).

2. Swivel-Screw tips were 'mushroomed', which deformed threads. (This was intentionally done to prevent loosening and loss. When such screws are removed, the threads are further deformed).

FWIW - On a number of Krag rifles, I have seen the 'Stacking' and 'Barrel-Band' swivel screws mixed-up.

Attached is a photo that may help identify and display their differences.

The damaged threads for the Stacking-Swivel Screw, on your Krag front barrel-band, may respond and be 'trued-up' by using the front-band retaining screw as a tool.

Insert the long smooth shank into the threaded lug until the screw's threads make contact. Carefully index and start the screw into the threaded lug. If the threads 'mesh', the screw will turn through and straighten the thread damage.

Yes, the band-retaining screw is also 26 TPI. (The same screw is used to retain a 1903 Sringfield front-band).

Attachment 88579

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Originally Posted by butlersrangers

The same screw is used to retain a 1903 Springfield front-band

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Wondered how long it would be until that came out...

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Originally Posted by browningautorifle

Wondered how long it would be until that came out...

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"Inquiring minds need to know":)


Just to give an update on my Krag stacking screw dilemma, last Friday(11-17), I took a good look with a very bright light into the threads of the stacking swivel and approximately in the middle of the threads there appeared to be a build up of "something" deep in the threads. I took a small needle pointed awl with a bend in the end and picked out whatever the material was. Wasn't rust, some hard brownish substance, rock hard. Couldn't see any thread damage, so took 'butlersrangers' idea and screwed the front barrel band screw in (lubed it first) and it screwed in with no resistance. Tried the stacking screw and went in and seated with no problem. Happy camper am I.

Took a look at the S&S website 'no4mk1t' posted, be a good site for obtaining scarce items, but at $6 for a screw, plus $7 shipping, pricey, but a last resort I guess. Very interesting info he posted on screw/thread pitch history. Wasn't aware of all the history behind the use of size/pitch, ie USS, UTS, SAE. Very interesting reads, esp. the formula's used to obtain pitch/tpi. Reference the 03 Springfield in continuing the use of the USS threads, I wonder how long they did so. Wonder if Remington continued the use after they started their 03 manufacturing in the early 40's, assume so to continue the interchange of various same parts. 'butlersrangers', your mention of possible French influence is something I read also, might have been on the KCA Forum, might have been something you posted. Be interesting project to read upon.

Good information on the web about what was used in the late 1800's and early 1900's. Tried to find some information as to when firearm manufactures switched from the USS screw size/pitch to the UTS/SAE format. If anyone knows of any chart, listing, etc that gives the screw sizes/thread tpi of firearms made since say the late 1800's to present day, it would be very interesting. Went to a local gun show last weekend and talked to the gunsmith I mentioned in earlier post and talked with him about the Krag. He advised as to what most have posted here about the Krag's screws being odd size compared to what is used today. Advised he had a few taps/dies of early used screws and finding them is a hard search. Anyway, problem solved, thank you to all who posted info and advice. Was going to post info last weekend, but busy, busy. Happy Thanksgiving to all.

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Originally Posted by Der Jagar

Wasn't rust, some hard brownish substance, rock hard.

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Probably just cosmoline...nothing magic.

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Originally Posted by browningautorifle

Probably just cosmoline...nothing magic.

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That crossed my mind also, but have never seen cosmoline get that hard, the substance was almost like dried varnish or something similar, hard and brittle. The stock wasn't refinished though, still had linseed type org finish on it. Anyway, Krag is now complete as far as what it should have attached.

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Originally Posted by Der Jagar

the substance was almost like dried varnish

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That's right, but yes it could have also been dried varnish or motor oil. Lots of guys used to use any oil at hand and motor oil is so heavy as to turn to a varnish like coat after time. I've removed lots with mineral spirits and such.

:thup: Some guys still do it today. Talked with a LEO friend in my state who worked on dept and general population guns. Advised two of the worst he saw was one guy used super glue on the threads of a N frame S&W so they wouldn't back out during recoil, only problem when the guy tried to take the gun apart for cleaning--no dice. Another guy used some 90W gear oil on his semiauto Remington shotgun (for super lubrication the owner thought)--only problem was worked fine in his heated basement, but didn't work so well out in the cold duck blind. I've seen some pretty lame things done also in the years I've spent shooting and hunting.