I annealed my TR cases after 8 firings, and it has perhaps improved the consistency of the neck-tension. However, I don't think annealing will help with the problem raised in the op.
Case Head Separation Signs?
- Thread starter Scotty99
- Start date
You can get away with only neck sizing for quite a long time, particularly if the brass is and stays soft around the shoulder. Provided you are prepared to force the bolt closed once, inevitably, the shoulder has become an interference fit in the chamber. By force, I just mean a bit sticky, provided your bolt has a good camming action.
Not good for the bolt lugs etc. keep them clean and greased if you choose to do this.
It's not my way, but plenty still do it.
I've not heard that before. How does annealing reduce the risk of case-head separation?
paul o'
Well-Known Member
Found you this : The Science of Cartridge Brass Annealing , Incorrectly setting up the sizing die, by pushing the shoudler back more than needed can also make the case fail .
Interesting article, thanks; but which bit explains how annealing the neck/shoulder area of the case helps prevent case-head separation?
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enfieldspares
Well-Known Member
What I do is this if the cartridges are for use in but ONE rifle. Fire. Lubricate the case as for normal re-sizing. Now put black soot on the shoulder and neck using a candle.
1) Back off your FL sizing die. Run the case through it. You will see some of the soot scraped off down the neck.
2) Turn down the sizing die so that eventually all the soot has been scraped off the neck. This has given you a "neck size" but using standard FL dies.
3) Now turn down the dies from that position until the soot on the shoulder is compressed. It will not longer be a velvety matte black but a semi-matte and look flattened. Your FL die is now effectively re-sizing the case to the same length as the chamber.
4) Turn down the FL die maybe a 1/8th of a turn. The cases are now being sized to just a "tad" short of the chamber in that rifle to allow for a slightly dirty chamber or a hot chamber. Load one dummy cartridge but with neither primer nor powder using your normal choice of factory bullet at an appropriate OAL as a test cartridge. If that chambers and ejects without effort you are good to go and load the rest of that batch of cases with primer and powder at leisure.
Preserve how the FL die is set up and leave it like that for when you re-size any brass that has previously been fired in that one rifle. But don't leave it so if re-sizing brass once fired in another's rifle.
Why? As re-sizing is not only about sizing the neck and re-setting the shoulder it is also about ensuring that the head of the case is within a "one size should fit all" dimension. Some rifles have maybe chambers that will be larger at the head than in your one rifle. So if you used my four step method (not just mine I take no credit it is a commonplace well known practice) your cases fired in another's rifle may be still be too large at the head for your rifle.
1) Back off your FL sizing die. Run the case through it. You will see some of the soot scraped off down the neck.
2) Turn down the sizing die so that eventually all the soot has been scraped off the neck. This has given you a "neck size" but using standard FL dies.
3) Now turn down the dies from that position until the soot on the shoulder is compressed. It will not longer be a velvety matte black but a semi-matte and look flattened. Your FL die is now effectively re-sizing the case to the same length as the chamber.
4) Turn down the FL die maybe a 1/8th of a turn. The cases are now being sized to just a "tad" short of the chamber in that rifle to allow for a slightly dirty chamber or a hot chamber. Load one dummy cartridge but with neither primer nor powder using your normal choice of factory bullet at an appropriate OAL as a test cartridge. If that chambers and ejects without effort you are good to go and load the rest of that batch of cases with primer and powder at leisure.
Preserve how the FL die is set up and leave it like that for when you re-size any brass that has previously been fired in that one rifle. But don't leave it so if re-sizing brass once fired in another's rifle.
Why? As re-sizing is not only about sizing the neck and re-setting the shoulder it is also about ensuring that the head of the case is within a "one size should fit all" dimension. Some rifles have maybe chambers that will be larger at the head than in your one rifle. So if you used my four step method (not just mine I take no credit it is a commonplace well known practice) your cases fired in another's rifle may be still be too large at the head for your rifle.
I will try...
When fired, the case expands to fit the chamber, the neck and shoulder are pushed forward into the chamber and the case head is pushed back against the bolt face. If the shoulder neck and body are all the same hardness,the pull will travel further down the case body until it meets the thicker harder part of the wall just in front of the head section and that is the area where the plastic/permanent deformation will take place.
If neck and shoulder are softer they will still conform to the chamber, but because they can reform more easily they will exert less pull away from the harder part near the case head.
Alan
I can see what you mean.
However, I'd imagined that at the moment of firing the case would likely be shoved forward nearer (if not onto) the shoulder of the chamber by the striker anyway - at least, as far as the extractor will allow; and then the rapid rise in pressure would cause the case-walls to grip the chamber - thinnest bits of case-wall first, all the way back to the web - until finally the web/case-head (which doesn't expand/grip at low-enough pressure to prevent this) is pushed against the bolt-face resulting in the familiar thinning in front of the web.
Any road up, I think that annealing like to be a very distant second to setting the dies correctly when it comes to reducing the incidence of case-head separation.
However, I'd imagined that at the moment of firing the case would likely be shoved forward nearer (if not onto) the shoulder of the chamber by the striker anyway - at least, as far as the extractor will allow; and then the rapid rise in pressure would cause the case-walls to grip the chamber - thinnest bits of case-wall first, all the way back to the web - until finally the web/case-head (which doesn't expand/grip at low-enough pressure to prevent this) is pushed against the bolt-face resulting in the familiar thinning in front of the web.
Any road up, I think that annealing like to be a very distant second to setting the dies correctly when it comes to reducing the incidence of case-head separation.
Intriguing ain't it?
The shoulder may well be first to move...it might even be moving forward at the same speed as the bullet and following the base of the bullet forward...the neck itself wouldn't obturate until after the bullet had left the case....and given the reaction to the bullet's mass...maybe the whole case is pushed back to the bolt face before the bullet has cleared the neck?
Alan
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If that were so, would cases stretch just in front of the web?
Only if the case shoulder and neck were not softer than that area and did not move easily...QED?
Alan
If they are softer, will they not expand outwards radially to grip the chamber-wall more readily - and having done so anchor the case ready for the case-head, on its way back to the bolt-face, to stretch the metal just above the web anyway?
Is it not just in the timing? The case head would have moved back its few microns to the bolt face before the bullet will have moved forward its few millimetres along the case neck enabling the neck to expand radially behind it?
Before the bullet has left the neck and allowed the neck to expand radially and grip the chamber wall, all of the surfaces of the case are tapered and would readily move back to the bolt face in reaction to the inertia / mass of the bullet.
The shoulder area pushing out and contacting the chamber shoulder first would tend to assist in the backward movement of the case body and head? I.e. if the shoulder is soft enough to deform forward it will put little pull along the case body wall and maybe even a net push. Only if it is hard and goes forward en masse without the transitions reforming will it exert a pull on the case wall.
If we wait a bit longer I am sure @Sharpie will be along with a video of it all in slow motion to settle our conjecture!
Alan
I'm sure so - a video simulation would be interesting!
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