Reamer design question

[Edd]

In a perfect world. Perfect being the finish reamer and resize matched perfectly together you need at a bare minimum .003" over virgin brass. This works but just barely. If I ordered the reamer sets today I would go +.005" over virgin brass.
YMMV

You would order the finish reamer .005” larger than the new brass and the resize reamer the same size as the new brass?

 

[DaveTooley]

You would order the finish reamer .005” larger than the new brass and the resize reamer the same size as the new brass?

finish reamer +.005' over virgin brass
Resize reamer -.004" from finish reamer
Same on the shoulder. finish reamer -.004"
On new designs I never have less than .010" taper per inch on the body.

 

[Alex Wheeler]

@Alex Wheeler Trying to follow this. Would it be more logical to design the chamber (reamer) to fired and sized brass rather than virgin brass as the size of the case from the factory may be smaller or larger depending on the particular sizing die caused? Further wouldn't this be more important if you were to design a custom chamber reamer?

Fired and sized in what chamber and die? What we know is what the virgin case is which gives us an idea of how small the die can be and knowing how hard the brass is tells us how big the chamber needs to be to give enough squeeze. Theres no one size fits all. You need to understand the brass your working with.

 

[DaveTooley]

What Alex said times two.