257 Roberts bushing size

foggybottombob

Beginner
Dec 31, 2025
1
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I'm building a 257 Roberts. Will be using Nosler 257 Roberts brass. Does anyone here know what Type S neck bushing I need to use with Nosler brass to get a 0.002" neck tension?
 
Load a dummy round with a bullet, measure neck diameter, subtract .002" for your bushing size. I made an error once by not having the brass, bullets and the die on hand before determining bushing size, because some brass necks are thicker or thinner than others. I was off .001"
 
Load a dummy round with a bullet, measure neck diameter, subtract .002" for your bushing size. I made an error once by not having the brass, bullets and the die on hand before determining bushing size, because some brass necks are thicker or thinner than others. I was off .001"
This☝️
With the bushing dies I like to get one bushing on either of the 0.002” also.
 
Welcome aboard F.BB. I’ll be ordering a 257AI barrel from PAC Nor on Monday, will be following your build story as you share information. Have you a twist and bullet in mind for your build?
 
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