reloading "trouble shooting"

[switchsl]

I have done a fair bit of reloading, but this to me is strange. My brass is coming out shorter than when I first purchased it. Now I can see some case stretching from fire forming, and I only resize the neck... but my brass seems to be getting shorter each firing, not longer. Its a 30-06, fired in a win mod 70. I have never had this problem before, in any caliber, and not in this gun. Any insight? Maybe its time to have the chamber inspected by a gunsmith... Although the gun is about 13 years old, its only had about 300 rounds through it. I have measured from new winchester brass usually plus or minus 1 thousand, fire formed and resised it shrinks about 2 thousand, and then again untill it reaches as much as 10 thousand below spec. Im sure its no concern in accuracy or pressure spike but it is odd. There is no pressure signs, and no deformation at the head that is measurable. At .0005 expansion, I throw the brass out, usually bout 6 to 7 reloads. I dont anneal.

[redranger15]

I just got a reloader kit and in the process of reading my manual, so buy no means do I know what I'm talking about but I just read and I mean the book is in front of me and It say's "case neck growth is common with high-pressure rifle cartridges.Some cases may never grow;in fact, those that headspace on the case mouth may actually become shorter after repeated firings".What ever that means?

[switchsl]

If I am incompetant as Im sure is the case here, somebody please inform me. I assure you all I am no genius. My brass continues to shorten after each reload now to as much as 17 thousands. No sooting and no over pressure signs. My measurement tools and technique Im sure are accurate. The dia behind the neck is difficult for me to measure, but seems to be consistent to +/- .0015 This is a tough one because i have no jig to get the same distance from base each time

[foothillsman]

There are several things that can cause that problem. The most important one is to check the headspace, especially if it's a used gun. The reason behind this is that someone may have reloaded and was using loads that were extremely hot for the rifle. Over a period of time a headspace condition developed. This occurs to rifles who's owners try to turn them into a more powerful cartridge than they are and ignore max listed loads. Because of the enlarged chamber, when the cartridge is fired, The brass is pushed back if it is a mild or mid load and the brass fills in the rest of the chamber, thus you loose a bit from the neck.

Another reason is that this occurs is that the reamer used is new and you have a large chamber. When the shoulders and neck fill out under pressure, the brass needs to come from somewhere. Because you have backward thrust, most of it comes from the neck.

[switchsl]

The gun has been mine since it was brand new... in 1994 I believe, I made a mistake earlier the rifle is about 16 not 13. It has always been maintained and never loaded to be a 30-06 magnum so to speak. I did recently run 15 of 20 hornady light magnum factory loads through it, but I cant see that harming the chamber. I understand the brass has to come from some where, and I have witnessed some shrinkage of the o.a.l. of a case in reloading before, but it has always been no more than 5 thousands give or take a little depending on caliber and always after a full length resize or with new brass. After the first firing, the brass has always remained the same, lengthened by a few thousand or shortened by maybe 2. This new shrinking is consistent, and compounding, thats what raises my concern. Im concerned I may have a problem with the action of the rifle. I find no other explination for it.

[switchsl]

My currrent loads are 56.3 grains varget under a 125 nosler bt @ average 3068 win standard rifle primer
57.3 of imr 4831 under 180 nosler ct @ 2600 federal magnum primer
58 of 4831 under 165 nosler accubond and speer 165 grand slam @ 2835 and 2800 respectfully both with federal mag primer.

Maybe I have made a huge calculation error somehow, but in checking all my information I am well in my limits and as I said no over pressure signs, when working the loads I did reach some primer flatening, then backed off accordingly. The 165 in particular, was the only concern, as it is a high end load, and my primary hunting combo. There is no visual trouble with the bolt or action, but My eye is obviously not accurate within thousands of an inch.

[foothillsman]

Now I can see some case stretching from fire forming, and I only resize the neck...

and I have witnessed some shrinkage of the o.a.l. of a case in reloading before, but it has always been no more than 5 thousands give or take a little depending on caliber and always after a full length resize or with new brass

Switchesl,

I suspect that your chamber is on the big side. If you are neck sizing now instead of fl sizing as you did before, your brass body is not returned to specs and your brass remains short, so the second time you fire, the brass expands to the chamber wall but returns less than it did the first time and so on. Eventually it will stop but you will find that the brass at that point will not chamber as smoothly. At this point you will either decide toss the brass or you will need to fl size the brass again. That's the only thing that makes sense to me. Try full length sizing it and see if you get your neck length back. I suspect you won't get it all back because it may be easier for some of the brass to flow into the shoulder and thicken it up there than flow back into the neck. Some of what you lost should return. Good luck!