a funny thing about 1903 tenon threads

  • Last Post 3 weeks ago
Ken Campbell Iowa posted this 03 May 2023

so finally I get to stick my new project barrel ( Shilen sporter in 35 Whelen )  for a spiffy 1903  sporterized action ....... in the lathe and get ready to thread the chamber end ... 

maybe I better look at the original takeoff barrel first ... goofy coned breach and square threads ...  geeeeze ...

so i cut a test barrel stub just to test for proof of my scheme  ... hmmm .. mine don't look the same as the originals ... hmmm ..

hey, somebody screwed up the original barrel .. square threads are way too shallow ... square threads are supposed to be square !! ... minor diameter is same as width of thread ...  what thu ?? ...

these are 1.040 major and 0.999 minor ... ?? ... very shallow ...  ok, check those neat original drawings we posted here a couple weeks ago ... oh no !!! ... it calls for the same shallow threads ...  

ok, I  will just go with the flow and dup the original, even the useless coned breech ...


does anybody know if these shallow threads were used throughout the span of the 1903 life ?


kinda trivia ... maybe the weird threads came from the same design team as the funny coned breech ?

btw, that action is nearly dead on to the drawing specs ... I didn't even have to shave anything on the action ... it was quite square already ...

oh yeah, i had to epoxy a square bushing onto the barrel to get the original off the action ... first one that gave me that much trouble ... guess 110 years might do that ...


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4and1 posted this 03 May 2023

You need to grind the tool .052" wide and cut the threads .052" deep. Deburr the edges well.

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RicinYakima posted this 03 May 2023

Yes, that is the same thread profile from the 1819 Hall Rifle on to the M1. When tightened, the threads have equal tension on all, not like "V" threads that only have tension on the few threads against the abutment, the rest just float.

The cone breach was to allow the 220 grain Krag round-nose bullet to feed from the Mauser style magazine in the shortest length possible.  Not needed after the spitzer bullet of 1906, but never changed. 

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Lee Guthrie posted this 03 May 2023

Just an FYI.  NOE makes a nice mould design they call "Thumper" --- a 300 gr GC for the .35 Whelen.  My AI Whelen likes it, but it is a 1:12 twist from Shilen.  PS  Deer do NOT like it.

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Ken Campbell Iowa posted this 3 weeks ago

just a trivia update ... after consulting hundreds of 1903 guys ... finally i found that Frank DeHaas mentioned in his * Bolt Action Rifles * that the shallow square threads are indeed standard on the 1903.

Dang !! ... my copy is hiding somewhere under my stash ... would have saved me hours worrying about it ...

maybe it helped turn out 3 million rifles 2 minutes each faster ....

but those 20 thou deep threads ( standard would be 0.050 deep )  still look like they were stripped out on a late Friday shift ...



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Aaron posted this 3 weeks ago

Dang !! ... my copy is hiding somewhere under my stash ... would have saved me hours worrying about it ...

Frustrating isn't it? I do that all the time with the BP stuff. Had the info all along, had read it before, forgot I had it in the pile of documents I had printed or in books I had bought. Hopefully it's a "genius" thing. I doubt it is - more likely an "old guy" thing.

With rifle in hand, I confidently go forth into the darkness.

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