Short Case Problem

[steelyonfly]

So far, I have always trimmed my cases to the standard "Trim to Length."  I just pulled 20 338WM cases that were fired before and cleaned in a tumbler.  I only necked sized the cases this time before preparing to trim.  The trim to length is 2.490" for a 338WM.  I found 10 of the cases, before trimming, to be between 2.484" to 2.488".  Two more were 2.489" which I'll still reload.

All of the cases were: fire formed to my chamber, full length resized in the previous loading, fired in my rifle and not someone elses, and they are all Win cases I purchased new.  None of these particular cases have been loaded more than three times.  I've noticed this shortening of my cases in other calibers I reload even when they were only neck sized in a prior loading.

I would say that about 10-20% of the cases I have are under the trim to length after firing.  This time was 50%. 

Is it unusual to have cases shorten so much and so often?  Is there something to check in my rifle or in my reloading method?

[wsmnut]

I have seen this a few times  too.  Take a look at your lubrication process.  Might be that the necks aren't lubed enough and when the resizer ball goes down, it's shoving the neck down a few thousandths into the shoulder.  Also check the die set up again.  I had a lock ring creep on me once that really messed up my program, and a bunch of brass!
Normally brass grows in length after firing.

Good Luck!

wsmnut

[steelyonfly]

wsmnut,

I just checked into what you suggested.  It sounded like you could be right because Lee Collet die instructions suggest screwing in the die 2 full turns after touching the shell holder if you use a press that toggles over.  I think my RCBS Rock Chucker does this.

The only thing I find is that many of my cases are short before any resizing has been done.  The neck resizing step tends to lengthen the case by .001" to .002" - using my Lee Collet Neck Sizing die set as above.  Full length resizing lengthens cases by .003" - .004" - using my Redding Full Length Sizing die and set per Redding's instructions.

I think that I'm going to mark a few of my cases with their exact length, shoot them and then check the case lengths to see how they've changed.  I think this is about all I can do.

Any other ideas?  Anyone?

[steelyonfly]

Jkeen,

I noticed this on some of the brand new cases, as well, but all of mine have been fire formed now.

[demontang]

I've noticed my brass only grows when I size the brass. Neck sizing doesn't seem to stretch the case at all and firing them shouldn't stretch them much unless you are at Max loads.

[wadu1]

I have noticed that Winchester (New) cases run on the short side. Remington Nickel does not strech as much and I get more reloads out of them.