25-06 to .257 Wby re-chamber ?


Well-Known Member
Jun 7, 2004
It looks like everything is O.K. except the 25-06 neck O.D. is .290" and the .257 Wby is .283". I have a .257 Wby case fired in a chamber that I didn't cut and the neck O.D. now is .294". I don't like the idea of putting mikes on reamer flutes, and I don't have a case fired in a chamber that I cut, so I don't know if .294" is excessive for the .257 Wby neck after firing, but it seems like it is.

I don't expect the .257 reamer to clean up the neck of the 25-06 chamber except in front (for the .050" or so extra O.A.L). If I set the barrel back .308", the slightly longer Wby neck will completely clean up the old neck. I just hate to give up .3" of barrel if I don't have to.

I don't have to do this, it just seemed like a great way to use a good barrel.

I also posted on Weatherby Rifles Forum.

Experience or opinions ? Tom

On edit: change .291" to .294". Between my garage and study, my one brain cell decided it was .291" instead of .294"
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The SAMMI print for the .25/06 minimum chamber has a neck diameter of .2920 at the base of the neck -.291 at the front.
The Weatherby print for the .257 minimum chamber has a neck diameter of .290 - .288 case mouth .

This information was found in the NRA book " Handloading " ISBN 0-935998-34-9.

Run that reamer in .5 more just to make sure that everything is new .

Glenn; thanks for the info. I have just been using reloading manuals for case size info and adding .002-.006" for chamber neck size. I need more exact info on the reamers, since I won't put mikes on a reamer. I never knew that the neck of the chamber was tapered on any cartridge. A guy on another thread said that the neck on a 6.5 x 55 Swede was tapered. He was talking about the chamber, not the case, and I didn't snap.

Thanks again, Tom
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