Case head separation. How to avoid it?

Brianma65 said:
I backed the die out until I had no neck tension, then kept screwing it in until I got neck tension.
Using a fired 7mm brass from my rifle.

I made a dummy rnd and it fits perfect.

Is that all I need to do?

I’ve always just followed the die instructions and never had any issues with other calibers.
Just this 7mm, but I’ve read it’s common.

Also,I seem to have a lot of free bore.
I checked this by just starting the bullit,into the neck.
Then I chambered and closed the bolt.

I’ll get measurements when I get home, but seems like a lot.
Click to expand...

Different bullets will have different ogives that contact the rifling at different seating depths. You need to measure and log this OAL for different bullets you are using.
An easy way to set up your FL die so it sizes just the neck and not touch the shoulder, is to take the expander out. Then, using a fired case slowly turn it in like you already did while raising the case into the die. You will have a very noticeable sizing step on your neck as you keep turning the die down, turn the die in and lock it when 95% of the neck is sized, just want a small unsized portion just above the shoulder. Reinstall the expander and size all your cases (including the one you just used to set up the die). This provides plenty of neck tension and you didn't move the shoulder.
Brass will last a long time, and you will probably see accuracy improve as well.
 
Brianma65 said:
It’s a new Xbolt.
I was playing around with the die adjustment. Got almost 2 full turns back and the brass still fits.
Click to expand...

Backing off 2 turns isn't telling you much. Cases that have been fired in a rifle will usually go back in the same gun. The reason for backing out a turn is just to make sure that you aren't bumping the shoulder at all. No shoulder bump = no set-back. No set-back = no stretching to fill the chamber next firing. No stretching= no separation.

There's a degree of over simplification in there.
 
I understand that diff bullits will give diff results.

In this case I’m using Nosler partitions.
Recommended col is 3290 ,my chamber OAL length,for this particular bullit is 3340.
Not so bad.

My bullit diameter is .282.
My case inside diameter is .277.

My die is 2 1/4 turns above the Shell holder,or about 3/16 of an inch.

Sound good?
 
Brianma65

What you are doing is called partial full length resizing and not sizing the case neck 100%, and only slightly reducing the case body diameter.

And a neck sizing die will size 100% of the neck but not touch the case body diameter.

The problem with partial full length resizing and just neck sizing is eventually the shoulder will need to be bumped back to prevent hard chambering.

And right now you still do not know where the case shoulder should be using a Hornady cartridge case headspace gauge.

If you kept adjusting the full length die downward you would reach a point where the case would not chamber. This is because the die is squeezing the case body diameter smaller and the shoulder is moving upward in the die. This means you can make the case longer than the chamber when full length resizing. The trick is only adjusting the die downward until the case shoulder is bumped back .001 to .002.

Below in the illustration you can see the case becoming longer as the shoulder is squeezed forward in the full length die. Then the dies shoulder contacts the case shoulder and begins pushing the case shoulder back down. And when the die is properly adjusted the case shoulder is pushed .001 to .002 below the red dotted line. If you adjust the die too far down toward the green dotted line you will create too much head clearance and this will let the case stretch, thin and separate.

wm05ArY.gif


The problem with some belted cases is they will expand just above the belt and will need to be reduced in diameter to prevent hard chambering.

Chambers and dies very in size and and many times the resizing die needs to be adjusted up or down for the case to be a perfect fit in the chamber.

Below before fancy gauges you would simply place a *.010 feeler gauge between the die and shell holder. Then use thinner feeler gauges adjusting the die downward until the case chambers without resistance closing the bolt.

*.010 varies and is a plus and minus guesstimate as a starting point.

7FfXhJ7.jpg


Bottom line, at some point you will need to adjust the die downward and bump the case shoulder down in order for it to chamber without hard bolt closing.
 
bigedp51 said:
Brianma65

What you are doing is called partial full length resizing and not sizing the case neck 100%, and only slightly reducing the case body diameter.

And a neck sizing die will size 100% of the neck but not touch the case body diameter.

The problem with partial full length resizing and just neck sizing is eventually the shoulder will need to be bumped back to prevent hard chambering.

And right now you still do not know where the case shoulder should be using a Hornady cartridge case headspace gauge.

If you kept adjusting the full length die downward you would reach a point where the case would not chamber. This is because the die is squeezing the case body diameter smaller and the shoulder is moving upward in the die. This means you can make the case longer than the chamber when full length resizing. The trick is only adjusting the die downward until the case shoulder is bumped back .001 to .002.

Below in the illustration you can see the case becoming longer as the shoulder is squeezed forward in the full length die. Then the dies shoulder contacts the case shoulder and begins pushing the case shoulder back down. And when the die is properly adjusted the case shoulder is pushed .001 to .002 below the red dotted line. If you adjust the die too far down toward the green dotted line you will create too much head clearance and this will let the case stretch, thin and separate.

wm05ArY.gif


The problem with some belted cases is they will expand just above the belt and will need to be reduced in diameter to prevent hard chambering.

Chambers and dies very in size and and many times the resizing die needs to be adjusted up or down for the case to be a perfect fit in the chamber.

Below before fancy gauges you would simply place a *.010 feeler gauge between the die and shell holder. Then use thinner feeler gauges adjusting the die downward until the case chambers without resistance closing the bolt.

*.010 varies and is a plus and minus guesstimate as a starting point.

7FfXhJ7.jpg


Bottom line, at some point you will need to adjust the die downward and bump the case shoulder down in order for it to chamber without hard bolt closing.
Click to expand...
Big dep,as of today ,I have no gauges, only fingers and eyes:)

If I were to get 4 or 5 firings out of belted cases, I’d be satisfied.
Right now ,after adjustment of dies, I’m getting good neck tension( can not push the bullit back,from strong force,against the bench).
And there’s hardly any resistance on the resize stroke.
Smooth as butter.
I’m going to try these out and see if they’re suitable.

I’m only testing rounds for hunting ammo and will only put a couple of hundred rnds ,per year, through my 7mm.
 
350 Mag said:
Call me nuts....but I only reload my cases 1x IF I am shooting MAX loads.....then toss them.

If target loads I shoot maybe 2-3x max and toss them.
Click to expand...

you're nuts. But it's your $$

Get a Hornady headspace kit for your caliper. Along with Redding competition shellholder set, you can bump the shoulder 2 thou and life is good
 
Brianma65 said:
Big dep,as of today ,I have no gauges, only fingers and eyes:)

If I were to get 4 or 5 firings out of belted cases, I’d be satisfied.
Right now ,after adjustment of dies, I’m getting good neck tension( can not push the bullit back,from strong force,against the bench).
And there’s hardly any resistance on the resize stroke.
Smooth as butter.
I’m going to try these out and see if they’re suitable.

I’m only testing rounds for hunting ammo and will only put a couple of hundred rnds ,per year, through my 7mm.
Click to expand...

What you are doing will be fine for several firings. At the point where chambering becomes hard due to the brass losing elasticity, you can either FL size once, or toss the brass. Really at that point it should be annealed, but to me I've got my money out of the brass at that stage and toss it.
You are at least doubling your brass life sizing the way you are doing it now, maybe tripling.
And you have little fear of head seperation anymore, you have solved that problem.
 
todbartell said:
you're nuts. But it's your $$

Get a Hornady headspace kit for your caliper. Along with Redding competition shellholder set, you can bump the shoulder 2 thou and life is good
Click to expand...

I’m planning on getting some better gear, and ditching the Lee dies.
Just have so many projects and so little time:)
 
A Redding body die and a Lee Collet is a good and cheap combination to have the best of both worlds. You neck size only until needed and shoulder bump 0.001-0.002 when it gets hard to chamber. Unless you turn your necks then go with a good quality Bushing Die instead of the Lee.
 
Fastestmanalive said:
A Redding body die and a Lee Collet is a good and cheap combination to have the best of both worlds. You neck size only until needed and shoulder bump 0.001-0.002 when it gets hard to chamber. Unless you turn your necks then go with a good quality Bushing Die instead of the Lee.
Click to expand...

Uhh, the other way around. The Lee Collet Neck die doesn't care about the neck thickness, nor does it care about any neck thickness variations. It sizes on to a mandrel that is 0.002" under nominal bullet size.

If you turn your necks after the first or second firing, then you can go with a bushing die from that point onward.
 
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