split case necks.

[dvdcrr]

Hello,
I am shooting my Kimber 8400M 270WSM. Load is 64.5gr. RL19. 130 gr. Sierra bullets. This brass is once fired and reloaded. I am getting split case necks. This has happened 5 times. The gasses are punching or burning a notch right through the neck. Not totally to the mouth, but an elongated notch on the neck. Technically I guess that would be a elongate hole not a split. But anyway, what do I need to do here and has this likely hurt the gun. BTW the gun is a great shooter, even when this happens. Thanks!

[F. Guffey]

If The rifle was my rifle I would be worried about gas cutting of the chamber neck. I have one chamber that eats cases if I use Turkish ammo in one of my 8mm57 chambers. Out of 100 rounds fired I can expect 20 with split case bodies and or necks. Just guessing but the cases look as thought they were hit with shaped charges.

I formed 8mm57 cases from 30/06 cases and then pulled the bullets. I did not worry about tight necks because the 8MM has a generous neck, And then the bullets, the bullets have a waist like a dirt dauber I doubt anyone ever described the shape as hour glass, If the hour glass shape was caused by crimping there would be evidence of a crimp on the outside of the case neck, I found no evidence of a crimp on the neck. I paid $4.70 for 70 rounds at one time thinking I could use the powder and bullets if the primers were corrosive.

And then there was the problem of cleaning the barrel because they used streak-er bullets.

F. Guffey

[ShootistPRS]

Pictures would really help.
It sounds like the cases are being oversized and then expanding to fill the chamber. This hardens the brass and subsequent use causes the brass to split. Annealing the brass may help but getting a sizing die that is closer to your chamber is the cure.

[JeepHammer]

I would have the chamber checked. Even Kimber could have an occasional issue.

[603Country]

I’m with Jeephammer. The chamber needs to be examined.

[cw308]

dvdcrr
Your getting this with once fired brass & reloaded . How are you peeping & sizing your brass ? Are you having hard chambering or bolt lifts

[dvdcrr]

I am lubing the brass and running through Hornady New Dimension FL die.
Lets say I have fire 6-8 rounds where the neck got a notch burned through. Is that enough to harm the chamber. That I would need it checked.
I am going to start with different brass and go to a Redding or RCBS die.

[F. Guffey]

Split cases? I am the only shooter that has cases that can not expand as fast as the powder burns, I also have cases that take on the appearance of gas cutting. The case look as though they were cut with a shaped charge, I pulled down thousands of rounds to get rid of the cases and primers.

Hurt the chamber? Only in my chambers; I choose to use the case to cover the chamber, I choose not to use short cases, I want my cases to cover the chamber out to the beginning of the throat.

I find nothing entertaining about burning powder between the outside of the case neck and chamber; I want my case neck to expand to seal the chamber.

F. Guffey

[F. Guffey]

has this likely hurt the gun.

Hot high pressure metal cutting gas can cut the bolt face. I would think this would be a good time to learn to case the chamber, there are many shooters/smith/reloaders that can do that half hazard-ley and then there is the bore scope.

The cases could be too brittle to expand, there are reloaders that believe they can move the shoulder back when sizing and move it forward when firing. Reloading is very simple for me because I can not move the shoulder back and the worst thing that can happen to a case when fires is to have the shoulder move forward.

F. Guffey

[dvdcrr]

[Ifishsum]

I've had the same thing happen with one of my ARs earlier this year, I think it was a bad batch of brass but it had been loaded 3-4 times (usually I get more than that). I was at a match so I had to shoot what I had, had maybe 12-15 total split/burned through necks by the end. I haven't inspected the chamber with a scope or anything but it so far does not seem to have affected how the rifle shoots or functions is that's any help. Obviously it's something to try and avoid because it likely did cause some gas cutting in the chamber and enough of that will probably cause issues. I expect to replace that barrel in the next year anyway so it hasn't bothered me a bunch.

As to why it's happening, it could just be brittle brass. Could also be the die is oversizing the brass unnecessarily or a generous chamber. I'd start with the easiest or cheapest thing first and maybe try a different brand or lot of brass if you can. And try adjusting the sizing die to size the brass just enough to chamber easily.

[BBarn]

Perhaps the brass is too hard. Might try annealing the necks. I have had the same problem with 243 brass (Winchester headstamp). It's still early, but so far I've had no additional split necks after annealing (the same batch of brass).

[Wrought]

Brittle brass. I got this with old den 42 .06 military brass resized to .270. So i stopped that..

[griz]

I've had a few do that but only with cases fired maybe five times or so, and nowhere near the consistency of the problem that you are seeing. Like others here, my first guess is bad brass, but it wouldn't hurt to check the expander ball for damage on the circumference.

[RC20]

Not something I have ever seen.

Direction of the curl looks like outside to inside, not gas cutting from inside to outside.

Is that condition of the brass after fired or is it cleaned up?

Very interested in Unclenicks take.

[Roadkill2228]

I've these kind of partial neck splits. I think some batches of brass are just inherently more brittle and thus short lived. It hasn't hurt any of my guns to the best of my knowledge . When one considers that a barrel can be usefully accurate for thousands of rounds, each time being subjected to all that hot gas and friction and potential flame cutting, and that the barrel and receiver are made of the same kind of metal, it puts things into perspective. You could have a complete case failure and, while your action would probably need a mallet to open, your gun would probably be just fine provided this wasn't happening all the time. Consider the pressure and strain of proof loads, which arms makers must demonstrate their weapons can survive.
You say their once fired...is that once fired by yourself or did you get them from someone who wasn't honest with you. That could be an easy explanation.
A looser chamber will cause this more quickly, as the amount of work and subsequent metal fatigue on the brass with each firing and resizing is greater. My .243 is hard on brass like that, with casings coming to the end of their useful life just like this, the necks split. I've seen it in .270 as well, especially in the fired brass from a friend's specific 270 rifle (a browning). I suspect the chamber is not so tight in that particular gun.

[Roadkill2228]

Brass annealing might help prevent this problem.

[RC20]

What brass? Once fire in your gun, pick up?

Be interesting to see where this goes.

A gas release outside the case is not a good thing.

Not a clue if a fine line like that can do damage, not something to be take lightly though.

No way that a single shot will do that (should) even with the worst brass, not a split neck by my definition, that starts at the mouth.

Not anneal issue, its only two rounds.

[Mobuck]

You could try "orienting" your cases when chambering. That way you know if the split is happening in the same place in the chamber each time. WSM brass is worked pretty hard in the manufacturing process so it's quite possible some cases get work hardened early on. Incorrect brass stock quality control or improper factory annealing could easily result in some cases being brittle.

[OzeanJaeger]

I’ve never seen a split neck in uniform lines like that. As was said, that looks like the metal is rolled outside in, and not inside out from expanding gasses. To me it almost looks like it was hit with a cold chisel. I would bore scope your chamber. You need to see what’s going on in there, because that is mysterious.

[dvdcrr]

I dont have a bore scope. I looked in there with a flashlight and could not see anything too weird.....

[reynolds357]

Figure out how much the neck grew during firing and you will have your answer. If Kimber rifles are up to the same standard as Kimber pistols, I bet the chamber is cut wrong. Oversized, burr, spiral, etc. I guess the all important question is what does it do with factory loads.

[Cavitation]

This only happens with once fired brass right? no factory ammo has this issue?
If so its a Brass hardness,batch issue. Try annealing or throw it away and try another batch or brand. Sizing hardens brass. It may be extremely thin brass from the factory and sizing is all it can take.

[Cavitation]

double

[m&p45acp10+1]

Take the decapping pin out of your sizing die, and inspect the inside of the die. I had a similar issue a few years ago with a .221 Rem Fireball sizing die. There was a bur inside the area of the neck. I could have sent the die back to the company that made it, and they would have fixed or replaced it. I did not want to wait so I went to a local machine shop, and a machinist charged me $15 to clean up, and polish the inside of the die body, and to true the expander. The result was it stopped doing just what I see on that brass.

I think they call it galling inside of the sizing die.