Stretching brass

[TGVan]

So I have an issue I have never experienced before.
I'm sizing 7Rm brass, I just got the case length things from Hornady and I am all fired up and for the first time ever I am going to set my die to bump the shoulder back 2 thousandths. I measure, size, and bang. My brass is 5 thousandths longer than when I started, so I start messing around with things. I ended up bottoming out the floor sizes (2 of them) and getting the same result.

Quite frankly I am bumfuzzled. I tried everything I know and keep getting it longer. I even tried a brand new case. I pulled the expander/decap assembly out of the die. Tried extra lubes in the neck. I just ended up frustrated and put everything away.
RCBS, and Lee full length size dies. Also a Lee collet size die. Remington, federal, and Winchester brass. Hornady one shot spray lube, and the Hornady sizing lube that comes in the little tub.

Anyway that about covers that. Anything that might help me solve this would be welcome. Now I think I will hit the search bar and see if there is already something about this out there.

 

[MagnumManiac]

Firstly, even if you have bottomed out the die on the shell holder, there is slack in the system. Therefore, when you size a case, there WILL be a gap between die and shell holder unless you cam over, even slightly.

Secondly, as a case is sized, the case body is squeezed, that brass displacement elongates the case measured at the shoulder. This is your extra length.
Only pushing the shoulder will shorten it, if your die has a gap at the bottom when at full stroke, you need to tighten the die IN 1/12th of a turn, measure it and adjust until you match a fired case or size .001" less than that number.

Hope this is clearer than mud.

Cheers.

 

[TGVan]

I am getting cam over with the RCBS floor size die. With and without the decap rod assembly. Some of the brass is once fired in this rifle, and after sizing It is stretched enough I can't close the bolt on it. Oh how I love learning new things..

 

[bigedp51]

Chambers and dies vary in size and sometimes you need to tweak and adjust things to get the proper amount of shoulder bump. If you die is making hard contact with the shell holder with press cam over you might need to lap the top of the shell holder. This will allow the case to be pushed further into the die and bump the shoulder back more. Try lapping a few thousandths off the top of the shell holder until your case chambers.

NOTE, before lapping the shell holder see if you can adjust your die lower to get more shoulder bump. I have been reloading for over 48 years and only had to lap one shell holder for a very tightly headspaced rifle.

 

[BallisticsGuy]

http://larrywillis.com/

belted magnum collet body die... might just help.

I set up my belted magnums to have zero headspace and then neck sizing seems to work well but it means I'll have a few cases in every bag of 50 that simply won't fit because the belt is too wide which I end up having to discard because I'm too lazy to try turning belts down.

 

[cohunt]

try the redding competition shell holds (#6) they allow for different "bump" settings by using the shell holder
https://www.redding-reloading.com/online-catalog/35-competition-shellholder-sets

 

[bigedp51]

try the redding competition shell holds (#6) they allow for different "bump" settings by using the shell holder
https://www.redding-reloading.com/online-catalog/35-competition-shellholder-sets

The Redding competition shell holders do not push the case as far into the die as a standard shell holder. These shell holders are .002 to .010 taller than a standard shell holder.

Most resizing dies will push the shoulder back more than needed, and the Redding competition shell holders will give you .002 to .010 "LESS" shoulder bump.

 

[TGVan]

I have some other brass that is waiting to be sized, once my weekend comes around again I am going to give this another try. I am going to measure both from shoulder to case head, and the full case and see what difference there is. This will likely be the last time I size any of this brass so I can afford to experiment a little bit to figure out what I am doing wrong.

 

[MagnumManiac]

I'll give you a scenario that may explain your situation.
I have a 375 Weatherby, it has a short chamber, actually .001" less than minimum spec in head to shoulder length.
The Redding die I have for it is longer than this when the shell holder is hard against the die.
Cases WILL NOT chamber, they are .008" too long.
My only option was to place a .010" feeler gauge under the case head during sizing, this was tedious, so I purchased another shell holder, turned .010" off the top of it, to allow cases to enter the die further, giving me .001" bump and fixing the problem of a short chamber and long die. The die is adjusted as normal, but allows the extra length to be SHORTENED by bumping the shoulder back.
That doctored shell holder stays with that die set for life.

Cheers.

 

[TGVan]

Ok, that's a bit easier for me to understand. I might have to resort to that. I do have another shell holder for that one already, might be worth a shot just trying the second one out and see what happens. Thanks for the advice, it's much appreciated.

 

[MagnumManiac]

Your welcome.

I have been handloading for, working on and building rifles since the 90's, this 375 had me kerfuffled when I discovered fired cases slipped back in with ease, but sized cases would NOT.
I even resorted to honing and polishing the die......to no avail.

Anyway, try the above, start with a .005" gauge to be safe and don't forget to raise the recapping stem, if using one.

Cheers.

 

[okie man]

Ok, that's a bit easier for me to understand. I might have to resort to that. I do have another shell holder for that one already, might be worth a shot just trying the second one out and see what happens. Thanks for the advice, it's much appreciated.

Are they the same brand as the dies you have? Sometimes it's best to use same brand shell holder as die! Measure both shell holders to see if they are the same. Things to look !

 

[Rich Coyle]

I turned off .010" from the bottom of a die to solve this kind of thing.

 

[TGVan]

I have both Lee and RCBS dies and shell holders for 7 RM. So I am going to experiment back and forth and see where I get my best results.