setting shoulders back

[swampratt]

You guys will love this.
http://www.accurateshooter.com/technical-articles/die-issues-when-bumping-shoulders/

So i have case head seperation on my .308 cases after 7 firings or so..so i get to playing with my press and some fired rounds.
I marked the shoulder of a case with a sharpie and set my die into the press and backed it off 3/4 turn from touching the shell holder..
The shoulder was not marked..I twisted it in and sized till it was marked.
I had seen marks at 1/8 turn out from touching the shell hoder,..

Now i researched and found the above link..
Man that chamfered tool for measuring looked neat...

Yep i went to my garage and found a tool already made that fits right on the middle of the shoulder for my .308

 

[swampratt]

Ok so now i got a precise measurement of my fired case.
with tool installed over the top of the neck my overall length was 2.2535" of the fired round
I sized the case in my lee FLS die with the die 1/2 turn out from touching the shell holder.

The length is now 2.257" it actually grew longer!!!

OK so now i go 1/4 turn from touching..the measurement is now
2.2575" just a bit longer..and that length is the same as 1/8 turn out from touching the shell holder...

Now i seat the die to just touch the shell holder. 2.256"

Now i twist it in a 1/4 turn more after touching the shell holder.. 2.245" OAL
1/2 turn in produces the same.

SO
Fired case: 2.2535"
1/2 turn out 2.257"
1/4 & 1/8 turn out. 2.2575"
Touching is 2.256"
1/4 & 1/2 turn in 2.245"
So that bumped my shoulder back .0085"

I also looked at the shell holder die interface area when sizing cases...
Just because the shell holder touches the die without a case in it does not mean it will touch with the case in it.

Mine had a gap...due to the flex of the press..no i measured press flex while sizing .001"
Then i measured the gap with the ram all the way up with case in shell holder under pressure and i have .014" as measured with feeler gauges...
It is the die and press threads that give the clearance
I assume...even with the nut tightened all the way down
I still get airspace between die and shell holder.

I will find that happy medium point where the shoulder is not bumped back any and possibly have longer case life.

Sorry so long winded!!!!!!!!!!!!!!!!!
Fun with ammo.

 

[swampratt]

Some more pics.
This is how far in i turned my die after contacting the shell holder to bump back the shoulder .001" from the fired measurement..
Yes i have played some more.
Barely 1/8" turned in past touching.

 

[Calamity Jake]

If your 308 is a bolt gun then set your Fl size die so it sizes only the neck and part of the body with out touching the shoulder.
This should solve your case head seperation problems and extend case life.
If it's a semi auto, pump or lever gun then set the FL size die to just touch the shoulder or bump it back .001-.002 and call it good.
Also get the guns head space check by a good gun smith you should not be getting case stretching in a properly set up gun.

 

[swampratt]

I found that setting my die the way Lee suggested to set it would set the shoulder back .008" from the fired position.

I have a neck sizer die and my groups were much tighter when i set the die like Lee stated.
Neck sized around 1" groups.
FLS with shoulder set back .008" i would get groups under 1/2" and shot at 200+ yards they would stay between around .8"

Now that i can actually measured how much i am setting the shoulder back.
I hope setting it back .001 or .0000 the accuracy does not go away..

Only way to find out is to shoot more ammo

I have never seen a gun that after Full Length Sizing the brass that the brass will not grow.
All my brass grows like that in my bottle neck rifle stuff.
I see this stated a lot.
"Also get the guns head space check by a good gun smith you should not be getting case stretching in a properly set up gun."

So are you saying cases will never stretch in a properly set up gun..?
If so what is a set up gun?
If cases never stretched or grew then the cases would last forever if you annealed to keep hardness in check.

I think my issue came down to how Lee stated to set the die up.
Either way ,,it shoots awesome ..and i hope it still will once i load some with this new shoulder length.

 

[Driller]

So i have case head seperation on my .308 cases after 7 firings or so..View attachment 33975

What brand of brass did you have the separation with?

 

[ASP785]

In all of my setups the brass will still grow. Eventually I will have to bump the shoulder back. Typically this is after 5 or 6 firings. In a semiauto gun I always bump the shoulder back 0.003" to 0.004" for reliability.

Money well spent: http://www.hornady.com/store/Headspace-Gauge-Kits/

 

[swampratt]

It was winchester brass.. but i have not fired federal or rem brass that many times as the initial accuracy was not there.
So that brass i have is usually 2x fired or maybe 3.
I found this reading...EXCELLENT read.

http://thefiringline.com/forums/showthread.php?t=347313

With my now new tool to measure how much my shoulder is set back and reading around and doing a bunch of measuring i have come to the conclusion that my case life was shortened by setting the shoulder back .008" each time.
Way too much stretching and shrinking going on.

The case head web area that is cracking is "Pressure ring" as the guy called it on his measurements is .469"
My die sizes that area down to .467" so not pinching it down too much.

I will be bumping my shoulder back less and do some testing..but for now i have 70 rounds or so set up to hunt with..
Need to score more winchester brass.

MORE measurements for .308
.308Win cartridge dimension from head to datum is 1.634Max, 1.627"Min.

The .308Win chamber to the same 0.400" datum is 1.630" to 1.640".

My fired case measures 1.637" to the 0.400" datum.
Which i assume is fine since the case grows to the chamber spec and slightly relaxes after the initial bump up from firing.

 

[Calamity Jake]

"So are you saying cases will never stretch in a properly set up gun..?
If so what is a set up gun?
If cases never stretched or grew then the cases would last forever if you annealed to keep hardness in check."

If the gun has minimum or close to minimum head space from the factory then it is set up right.
Talk to a bench rest shooter, they neck size only and will shoot the same 5-10 cases for up to 50 shots without
ever setting the shoulder back, of course there gun has minimum head space..

I have 30-06 brass that is dedicated to one rifle(a milbolt rifle at that) that has over 50 reloads on them, after the first firing in said rifle
the brass has never been FL sized and the shoulder never set back any, I anneal after 10 firings and neck size with a Redding
bushing NS die.
I have the same setup for a Rem. 788 in 222 I PD hunt with, I neck size only, no case stretch.

 

[swampratt]

That is nice amount of firings from cases..
I will be experimenting with this ,,hopefully my brass will live a longer life.
I appreciate all the input on the subject .