Case Head Separation?

[Sturn88]

[Klem]

Are these cases sized?

[Sturn88]

Are these cases sized?

Yes they’ve been resized

[Gusmeister]

They look like they have been sized and the ring is from the sizing die. Really can't tell from the pics. Did the brass stretch a lot?

[Klem]

In that case (pardon the pun) the full-length squeeze down at the web is from your die.

Incipient case separation occurs higher up the case, roughly in the middle. The tell-tale separation trench will be in the inside of the case, not outside. A paper clip bent at right angles at one end and stroked along the inside of the case will let you know if there's any excessive case stretching going on.

What FL die are you using?

[grendelnubi]

I have heard you can take a curve pick and run it down the inside of the case to feel for the first signs of brass cracks. Haven't done it myself.

I have hornady brass that has had 9 plus reloading and I have not seen the first suspect case. I would measure the outside case diameter before and after the next firing and see if there is any signs of a bulge. I would bet if there is, your lugs are unlocking prematurely, exposing this section of the brass to pressure. If not, then it maybe resizing as suggested.

[Sturn88]

They look like they have been sized and the ring is from the sizing die. Really can't tell from the pics. Did the brass stretch a lot?

Since it’s the first resize, I can’t really know exactly how much it stretched. I trim my brass to 1.515 and as far as I can tell the longer cases were in the 1.525 range prior to trimming

[Sturn88]

In that case (pardon the pun) the full-length squeeze down at the web is from your die.

Incipient case separation occurs higher up the case, roughly in the middle. The tell-tale separation trench will be in the inside of the case, not outside. A paper clip bent at right angles at one end and stroked along the inside of the case will let you know if there's any excessive case stretching going on.

What FL die are you using?

Im using the Hornady custom grade dies.

[Klem]

Since it’s the first resize, I can’t really know exactly how much it stretched. I trim my brass to 1.515 and as far as I can tell the longer cases were in the 1.525 range prior to trimming

What he is referring to is headspace stretch. The length from the middle of the shoulder to the base. The Hornady gauge is a good gauge for this as you can measure loaded rounds. If you don't have one you can use a handgun case - any calibre close to .35" in diameter. In the photo it is a 9mm.


The bottom photo is how far a loaded round goes before it hits the inside. You're trying to measure the shoulder-to-base so unfortunately unloaded only. Still good for setting up your die to bump .003". I recommend the Hornady gauge at some stage (I wonder if a longer handgun case like a .357 might work...anybody?).

All this is unrelated to neck creep which is what you were referring to.

Apologies if you know this already.

[Sturn88]

What he is referring to is headspace stretch. The length from the middle of the shoulder to the base. The Hornady gauge is a good gauge for this as you can measure loaded rounds. If you don't have one you can use a handgun case - any calibre close to .35" in diameter. In the photo it is a 9mm.
[ATTACH=CONFIG]13762[/ATTACH]

The bottom photo is how far a loaded round goes before it hits the inside. You're trying to measure the shoulder-to-base so unfortunately unloaded only. Still good for setting up your die to bump .003". I recommend the Hornady gauge at some stage (I wonder if a longer handgun case like a .357 might work...anybody?).

All this is unrelated to neck creep which is what you were referring to.

Apologies if you know this already.

I did not know that. Thank you for explaining that to me. I’m still relatively new to this and have been trying to absorb every bit of information I can for the last few months. That is not something I’ve measured

[Klem]

Sturn,

Not a problem...Headspace is important because if you have too much of it your cases will rupture before they can be supported by the chamber. Brass is designed to expand but can only do this so much before it bursts like a balloon. If you have too littell of it you simply won't be able to close the bolt. Too much is dangerous while too little is safe but obviously no good.

Your biggest stretch is typically from firing a factory round or a new piece of brass. Fresh brass is the strongest it will ever be so unless you have a chamber reamed by an incompetent or crazy person you will be fine. After the first firing which you have little control over then you want to bump the shoulder only enough to ensure reliable cycling. For auto loaders that's about .003". If it's a bolt gun you have a lot of compound leverage when closing the bolt so .001" will do. If you bump the case any more than this you are working the brass unnecessarily and this will shorten its life. Or you can bump it so much that it will rupture next time you fire it.

My advice is to measure your case after firing with a handgun case and set the die up for a .003' bump. So, unscrew that sizing die which is crushing the cases too much anyway and with a measured fired case keep screwing it in by quarter turns until if starts to bump/shorten the case. Stop screwing at .003" and lock the ring (you are loading for an AR yes?). That way you can unscrew it from the press and screw it back in without going through this initial slow measuring process every time. Then you will have brass that is closest in shape to your chamber that will last a long as possible. It may not be able to be fired in any other gun but if you only have one AR the Bob's your Uncle! If you have more than one AR you will have to load for the tightest chamber or keep the brass separate and get two dies. Or go through the measuring process each time.

'Beware the man with one gun.' (Yes, yes, but that's boring!).

[montana]

What he is referring to is headspace stretch. The length from the middle of the shoulder to the base. The Hornady gauge is a good gauge for this as you can measure loaded rounds. If you don't have one you can use a handgun case - any calibre close to .35" in diameter. In the photo it is a 9mm.
[ATTACH=CONFIG]13762[/ATTACH]

The bottom photo is how far a loaded round goes before it hits the inside. You're trying to measure the shoulder-to-base so unfortunately unloaded only. Still good for setting up your die to bump .003". I recommend the Hornady gauge at some stage (I wonder if a longer handgun case like a .357 might work...anybody?).

All this is unrelated to neck creep which is what you were referring to.

Apologies if you know this already.

This was news to me Klem, and I thought I new everything thank you!

[centerfire]

In addition to what Klem said, cases will stretch well beyond safe headspace on the first firing without case head separation. Short of a manufacturer's defect or OOB detonation, you've really got to work brass before the head will separate.

[LRRPF52]

It's very common to see sized brass look like that.

If you're overworking it, you will see early deformation and thinning of the wall at some point.

The paperclip/dental pick method works for checking inside the cases to see if a thin ring has formed.

I use the Stoney Point/Hornady gauges myself to control shoulder location for headspace.