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Old February 8, 2013, 04:57 PM   #1
308Fan
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Join Date: February 4, 2013
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Headspace Variation

I'm another newbie looking for information/advice on reasons for variations in headspace and methods for minimizing it - specifically for .308 Win used with Rem 700 rifle.
I've read the books, I have the tools (but do you ever have enough?), and I'm continuing to research. In one of my early experiences, I was unable to chamber some reloaded ammo in spite of using a Wilson case gauge. I've since bought an Innovative Technologies headspace gauge. There are many choices out there, but this one makes sense for me and, based on subsequent results, I am confident in the measurements.
In order to control as many variables as possible in developing loads, I measure the headspace of each case (for my rifle). I've found that even the same batch of casings can vary as much as 0.005" after resizing. I'm currently using casings with a head to bolt face clearance of 0.0015" - 0.0035" (sorting out those that are undersized), but would like to do better.
I'm using a Dillon 550 press with a Dillon full length sizing die. I upgraded the die to the carbide version which tightened the tolerances some. I've also been experimenting with case lube - type and method of use which has yielded some improvements as well.
I am not too surprised to see large variations in range brass, but had hoped for better results in cases from the same lot (brand has not been a big factor). Perhaps I'm expecting too much from my equipment.
Any advice would be greatly appreciated.
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Old February 8, 2013, 06:22 PM   #2
243winxb
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Join Date: July 26, 2011
Posts: 839
Your doing great. Shell plates can be different at each station. This will make a difference if the FL die is contacting it. For a more perfect shoulder bump, a single stage press with Redding Competiton Shelll holder Set may produce better results. When the shell holder contacts the bottom of the FL die with the same pressure, the brass spring back is the only variable.
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Old February 8, 2013, 06:29 PM   #3
Crusty Deary Ol'Coot
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Join Date: November 19, 2009
Location: Deary, Ideeeeeeho
Posts: 512
308fan,

Welcome.

A rule of thumb is to always size brass fired in YOUR CHAMBER, the minimum amount need to allow the sized brass to again chamber in YOUR CHAMBER!

If you will send me a "PM" with your personal "E" address, I'll send you a document which addresses the situations you are speaking of.

Same offer for anyone.

What your are looking at here is the issue of manufacturing tolerences, and how to properly set up your dies to minimise the problem.

I don't know about Dillion, but although RCBS makes very good equipment, their set instructions fall way short of reality. Hornady, also a good equipment manufacture, includes a "foot note" which helps to adjust for the problem.

However, even Hornady does not go far enough in addressing the situation and how to correct for it.

Crusty Deary Ol'Coot
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Old February 8, 2013, 06:31 PM   #4
F. Guffey
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Join Date: July 18, 2008
Posts: 2,317
Any advice would be greatly appreciated?

“In order to control as many variables as possible in developing loads, I measure the headspace of each case (for my rifle)”

Sounds great, Larry Willis makes a case comparator, not a head space gage, the case has a length and the chamber has a head space designation. For your 308 there is a minimum/maximum, the difference is .010”, nice to know. I determine the length of the chamber first, I form then fire, everyone else fires then measures, I measure first then fire, all I have to size cases are presses and dies with shell holders. My opinion, a reloader that understand sizing and controlling the length of the case does not need Larry Willis's case comparator, a reloader with minimum shop skills can make a case comparator with the most fundamental of tools.

”I am not too surprised to see large variations in range brass, but had hoped for better results in cases from the same lot (brand has not been a big factor). Perhaps I'm expecting too much from my equipment.
Any advice would be greatly appreciated”

I have purchases once fired cases from the range, without Larry Willis's case comparator, I have measured and sorted cases in groups based on length, no surprise when checking head stamps they matched. My favorite fired case are those fired in trashy old chambers, because I control the length of the case from the head of the case to its shoulder/datum I can use the long cases to off set the effect of a long chamber. For everything else there is the 280 Remington.

Moving the shoulder forward is a matter of chambering a round and pulling the trigger when fire forming.

F. Guffey
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