Case headspace?

[TrxR]

Im assuming how many firings it takes the brass to completely expand depends on the brass , load, and chamber?

So my question is I am going to be reloading for a .223 wyld AR 15 and was thinking that i should just measure all my fired cases the set my die to bump the shoulder back in the longest one 2 -3 thousandths ? Will my idea work or should i bump back further? The measurements will be taken with a Hornady comparator.

Thanks

 

[BlackSheepBrass]

If it is a bolt gun, bump it your 2 - 3 thousandths so it will chamber and close the bolt reliably. This is once you have fire formed the brass in that particular rifle. If it is fired in a different rifle, F/L resize and then you can just bump your shoulder back or neck size on the subsequent firings.

If you are using an AR-15 platform, or any other semi-automatic I recommend you do not set your headspace to "bump" 2 - 3 thousandths. I have my camdex set up to -0.003" for headspace. More conservatively you could set it at 0.000 for reliable functioning. Mine is set at that specification due to my brass has to chamber in "any" rifle.

 

[TrxR]

So you saying not to bump the shoulders of the fired brass back 2-3 thousandths? So for example if my fired brass measured say 1.469 you wouldn't bump it back to 1.466?

 

[mustang979]

It's an ar, why not just full size them?

 

[Mystic Precision]

Im assuming how many firings it takes the brass to completely expand depends on the brass , load, and chamber?

So my question is I am going to be reloading for a .223 wyld AR 15 and was thinking that i should just measure all my fired cases the set my die to bump the shoulder back in the longest one 2 -3 thousandths ? Will my idea work or should i bump back further? The measurements will be taken with a Hornady comparator.

Thanks

Go with 3 thou and watch for case head separation. If you start to see some, then reduce by 1 thou.

Remember that you are sizing 3 thou SHORTER then the CHAMBER HEADSPACE... a fired case may be short, long or somewhere in between. You need to know the chamber headspace length

Best to take 20 cases and just load them 4 to 6 times and see what happens. An AR running properly with moderate pressures loads and proper gas cycling, will not stretch the cases much so bumping the shoulder 3 thou shouldn't lead to any separation

YMMV.

Jerry

 

[bigedp51]

Below in the photo is a once "fired" case from my AR15 carbine in a Hornady cartridge case headspace gauge at 1.4675. I then set my full length die to bump the case shoulder back .003 when full length resized.

The thumb rule for a bolt action is to bump the shoulder back .001 to .002 and for a semi-auto you bump the shoulder back .003 to .006.

Just remember chambers and dies vary in size, example I have a Lee full length .223 die that will reduce the case diameter more than my RCBS .223 small base die. And this same Lee die will also bump the case shoulder back further than the same RCBS small base die. The instructions for your resizing dies and making hard contact with the shell holder are to insure the cartridge will fit in any chamber. You do not have to do this with "your" rifle and with minimum shoulder bump the cartridge will be a custom fit in "your "chamber.

Below all you need to do when full length resizing for a AR15 is bump the shoulder back approximately .003 below the red dotted line.