Curious neck/shoulder case rupture.

[ar addict]

Annealing is your friend. If you full length resize, if you neck size, if you Ackley any cases, or make cases out of a case. like 17 fire ball or 300 blackout from 5.56.

 

[drstrangelove]

The Lazy full size as you call it, with camming over on the shell plate, generally works, but if your chamber is too long, you will need to adjust for that. Rounded shoulders are the result of setting the shoulders too far back.

 

[Xmark1]

Haven't pulled out my headspace checker to verify the exact shoulder position, but standing the cases up, all are the same length, and all shoulders at neck and body align. That was a D'oh photograph, and as commented on by @Xmark1, screwed up the analysis by rubbing the cases with steel wool.

I think the band you may be talking about are the bite marks from my bullet extractor - seems I seated a bullet too deep and went to pull it out to reseat, but grabbed the case neck first. Nowadays, if I do that, I'll toss the case into my scrap pile.

In all my 7 rem mag and 338 Win Mag reloading, never bumped shoulders, always did the lazy "full size". Guess I'll start doing that on the 338.

Those bite marks are crimp marks. I have the dies to make the same exact crimp mark & crimp.

 

[Local Loader]

The Lazy full size as you call it, with camming over on the shell plate, generally works, but if your chamber is too long, you will need to adjust for that. Rounded shoulders are the result of setting the shoulders too far back.

I'd have to agree with this. It looks like those cases weren't annealed and were over stressed do to excess space and over stretching. Unannealed cases are more prone to shoulder cracking than annealed if there's excess space. Metal fatigue sucks.

 

[P7M13]

Those bite marks are crimp marks. I have the dies to make the same exact crimp mark & crimp.

Yeah, Lee FCD can make those marks. What crimp dies do you have that make that mark?
Rifle dies don't crimp that I'm aware of - at least none that I have do. There is no need if your neck tension is properly set.
I will use FCDs on cartridges for AR types.
The bite marks are also the ones from the Hornady Bullet Puller, which I use. Recently pulled many dozen 284 Win and tossed the cases where I had grabbed the case instead of the bullet. Left those same marks. Have brass coming out of my ears, so don't want to deal with goobered brass.

 

[Local Loader]

All my dies have a taper crimp function built-in, pistol and rifle. I add a crimp to give me smoother feeding from mags. I haven't needed to use a FCD for any of my AR loads but each their own on that.
If you can get a hold of some forms you could metal your scrap and make your own casings if you've got a lot.

 

[Xmark1]

Yeah, Lee FCD can make those marks. What crimp dies do you have that make that mark?
Rifle dies don't crimp that I'm aware of - at least none that I have do. There is no need if your neck tension is properly set.
I will use FCDs on cartridges for AR types.
The bite marks are also the ones from the Hornady Bullet Puller, which I use. Recently pulled many dozen 284 Win and tossed the cases where I had grabbed the case instead of the bullet. Left those same marks. Have brass coming out of my ears, so don't want to deal with goobered brass.

Many years ago, I used to crimp my 5.56, 308, & 30-06. As a newbie I wanted to avoid setback. Something everyone was talking about back then.
Now days, as I have developed into a high precision long range shooter, I no longer crimp. I rely solely on proper neck tension.

Here is a picture of my Lee Crimp Dies for .308 & .30-06



Back when I was crimping, I preferred this crimp over a roll crimp or a factory taper crimp, because those kinds of crimps can distort the case sizing as well as profoundly deforming the bullet shank!
I don't crimp any of my handgun loads anymore either. It is either proper neck tension or the brass is recycled.

 

[P7M13]

If you can get a hold of some forms you could metal your scrap and make your own casings if you've got a lot.

That's a whole 'nuther ball of wax. Though, yes - a hoarder. >100 lbs scrap brass, same for copper, and ~1/2 ton of Lead.

I don't crimp any of my handgun loads anymore either. It is either proper neck tension or the brass is recycled.

So you don't flare your pistol cases for bullet seating? Eeek.

 

[Xmark1]

That's a whole 'nuther ball of wax. Though, yes - a hoarder. >100 lbs scrap brass, same for copper, and ~1/2 ton of Lead.

So you don't flare your pistol cases for bullet seating? Eeek.

Nope. Just a good deburring.
Flaring caused additional work hardening and detracts from neck tension.
Also, for pistol. I use Hornady Custom Demention New Grade dies that self-center the projectile as it approaches the case mouth, with a sliding alignment tube.

 

[Local Loader]

That's a whole 'nuther ball of wax. Though, yes - a hoarder. >100 lbs scrap brass, same for copper, and ~1/2 ton of Lead.

Oh I know it is, just figured it'd be an option since he said he has it coming out the ears. Was more of a failed joke I made.

 

[DizzyJ]

338 Win Mag, Winchester M70
Nosler 250gr E-Tip bullets.
Vhitavhouri N165 Powder
Doing a load work-up from 62-75gr to find nodes.
Starting at 62gr
Cases were full length sized
Zero other pressure signs.
Q: What are potential causes?
View attachment 1088304

Do you have an annealer?

 

[drstrangelove]

Do you have an annealer?

Anybody who owns a gas kitchen stove has an annealer. 6 seconds to the tip of the blue flame while you roll the brass between your leather gloved fingers. Get the neck and shoulders. Dip in cold water to cool. Will not harden.

 

[Pepe-lepew]

I would not waste any thought, time and money on annealing for this issue. The cases in that batch are already too far damaged. I would investigate the rifle and ammo. There could be major safety issues with the rifle causing it.

Potential causes,

Headspace (belted case so the belt head space)
Chamber shoulder to far out
Bolt or barrel stretched or worn, increasing headspace
Die pushing the shoulder back too far when touching shell holder
Case originaly used in a rifle with out of spec chamber
Cases exposed to ammonia in storage or during cleaning.

 

[Stomper]

Do you have an annealer?

Anybody who owns a gas kitchen stove has an annealer. 6 seconds to the tip of the blue flame while you roll the brass between your leather gloved fingers. Get the neck and shoulders. Dip in cold water to cool. Will not harden.

You can get an anneal-eez for around $275…. Works great!

Annealeez – Annealeez

annealeez.com

 

[P7M13]

Do you have an annealer?

Propane torch, stainless rod, cordless drill.

The cases in that batch are already too far damaged.

I think I can rescue these with my acetylene torch and some silver solder! <j/k>
All good points, @Pepe-lepew , though I've put >100 rounds through this rifle, these ruined cases are once fired from this rifle, and I have never had the failure before. Ammonia? LOL. No blue tinges on the brass, inside or out. I figure it's work hardened.

 

[Local Loader]

If you have a sonic cleaner you can use it to test for ammonia usage. For me it turns the cases pinkish or copperish color of its been exposed to ammonia.