Selection of key reamer drawing dimensions to facilitate precision shooting

[Cassidy]

This post is intended to obtain feedback from you experienced precision shooters about (1) which are the most important - key - dimensions to select (A, B C, ... on the attached drawing) on a reamer drawing (to have the reamer made), and (2) how to determine (calculate) the dimension for A, B, C... etc, on the drawing for any given caliber/weight bullet. The aim here is not to have to call those who make the reamers for us (please don't reply, just call the reamer maker), or our gun smiths, though they are helpful, but for us to learn how to determine items (1) and (2) ourselves for our BR rifle barrels, because this is critical information. To help with this (I hope) learning exercise, I have attached a pdf of one of my BR rifle reamer drawing (which I have not ordered a reamer for yet) with (1) each dimension assigned a letter (A, B, C...) so you can refer to that dimension as A or B or C, etc in your replies, and (2) I have whited-out all the other information on the drawing. I havn't found this specific information in any reloading or precision shooting books, so I hope the collective expertise on this site can provide this information for site readers. I hope the pdf file presents OK on this post. Again, the intent is to provide information on how to determine items (1) and (2) for any given round, not for the the round intended for the attached drawing.

 

[dmoran]

T to Z (excluding X) - is critical to match your desired bullet you plan to use and its seating placement.
C and S - are critical of your desired neck diameter/clearance
N - is critical of your desired case length (and trim length)
B,D,E,F - are critical if you have desired sizing-die dimensions you want to meet.

All have relevance.....
Talking to the reamer maker and discussing the intended plans, is critical important to having one ground special to fulfill all desires and demands - IMO

My 2-Cents
Donovan

 

[Cassidy]

Thanks, Donovan! It might be easier for responders to address only one dimension (or set of related dimensions) at a time, cause there are many dimensions to talk about.

 

[dmoran]

Attaching a labeled print, of my own interpretations (others may word things differently).
Donovan

 

[Cassidy]

Your drawing with labels help a lot, Donovan.

 

[40X Guy]

Outstanding Donovan! Your post of the print clears up a lot of unexplained measurements!

Frank

 

[Phil]

Yet another excellent contribution to the site.

Thanks Donovan,

Phil.


P.S....You had posted drawings of different weight bullets in different free bores to show how much case capacity was compromised, any chance you still have these, they were also a huge help.....for me anyways.

Visuals always eliminate questions, at least for me.

 

[dmoran]

Edited in a case + bullet into the print (attached).
Neither are proportionate, just roughly drew them, to represent placement.
Donovan