Concentricity Question

11 March 2017, 23:20

Ray Fryar

Hello all, just finished checking the concentricity of some loads and found a couple out of 50 or so that did not meet my specs, this got me to thinking what do other people do when they find this situation. So here is the question what do you do when you find some of your loads do not meet your concentricity specifications. Do you fix them and how? do you dissasemble them and start over or something else. Thanks in advance for any and all comments on the subject.

11 March 2017, 23:47

ted thorn

On ammo that I'm trying to print small groups with I fix them if they run out past .005 TIR

I use a Sinclair type concentricity gauge to check runout.

I use a Tru-Tool type block for "bending" the necks back into C/L

Trutool

For general hunting ammo I just use it without checking run out

11 March 2017, 23:55

Leo L.

Shoot them, and see what happens.

12 March 2017, 00:26

AFRICAN LEADWOOD

To me it would seem impossible to "fix" them. I've always wondered about those ideas amd tools. Pushing on one side will change tension on the other and essentially bend the case mouth and neck open one would think....

12 March 2017, 00:55

bigrdp51

In a factory SAAMI chamber a full length resized cartridge is supported in the rear by the bolt face and the bullet in the throat.

The body of the case does not touch the chamber walls and "guide or align" the bullet in the throat.

The only part of the case that touches the chamber is the case shoulder.

The late Jim Hull of the Sierra ballistic test lab and compeditive shooter jokingly said the following....

"The case should fit the chamber like a rat turd in a violin case."

I have both runout gauges below.

The hornady gauge on the left holds the case as it would be held in your chamber and reads half of what the other gauge reads. And the RCBS gauge spins the case on the body, and a full length resized case body does not touch the chamber walls.

The U.S. Military considers ammunition with .003 or less runout to be match grade ammo.

12 March 2017, 01:15

wasbeeman

The few that exceed my standards (don't laugh), I put a magic marker X on them and then shoot them. I shoot them separate from my match ammo but see if they go into the same group. Quite often they do.
Then I reload them and give them another chance. If they still don't prove up, into the scrap bucket they go.
I actually prefer to fire cull my brass. I don't check run out on my hunting ammo.

12 March 2017, 05:14

Ackley Improved User

quote:
Originally posted by bigrdp51:
In a factory SAAMI chamber a full length resized cartridge is supported in the rear by the bolt face and the bullet in the throat.

The body of the case does not touch the chamber walls and "guide or align" the bullet in the throat.

The only part of the case that touches the chamber is the case shoulder.

The late Jim Hull of the Sierra ballistic test lab and compeditive shooter jokingly said the following....

"The case should fit the chamber like a rat turd in a violin case."

I have both runout gauges below.

The hornady gauge on the left holds the case as it would be held in your chamber and reads half of what the other gauge reads. And the RCBS gauge spins the case on the body, and a full length resized case body does not touch the chamber walls.

The U.S. Military considers ammunition with .003 or less runout to be match grade ammo.

The Hornady run-out gauge shown above can be used to help eliminate non-concentricity - easy to do and helps in most all cases, but does not always completely straighten out the cartridge.