Comments on: TECH Tip: How to Reduce Run-Out with Seating Dies

By: Elvan Goode

Elvan Goode — Sun, 02 Apr 2023 21:05:32 +0000

I have tested some reloads out of my Lee dies that had .016” runout. Some of these rounds were difficult to chamber and after ejecting said round, abrasion marks were noticeable on the bullets where they were contacting the throat during chambering. Could this high level of run out cause pressure issues and/or accuracy issues?

By: PracticalTactical

PracticalTactical — Fri, 14 Jun 2019 14:28:39 +0000

I’ve found that the amount of neck resizing affects runout.

Think of it this way…

If you have 0.002″ clearance between neck and chamber of loaded round, you will be resizing maybe 0.004″, so you could theoretically get up to 0.004″ runout

If you have 0.010″ clearance between neck of loaded round and chamber, then you will be resizing 0.012″ and could theoretically end up with a max possible runout of 0.012″

So the less clearance between neck and chamber, the easier it is to produce concentric ammo.

By: mark

mark — Mon, 24 Oct 2016 08:02:06 +0000

O-Ring method is used only for FL die or for seating die too?

but what about competition seating dies, which have sliding sleeve that centers the case no matter of position of the whole die? this needs O-Ring method too for better performance?