Lapua brass problem

[Nelama]

Hi,

I recently got a CZ 527 grendel, so far the rife is amazing, shoots really well and accurate.
I got 200 lapua brass, shot them first time all good, however, on the first resizing I get this belts on some cases, some more then others, it is like 1 in 7 have this problem

I've attached some pictures.

Could you guys help me see where I'm going wrong?

this does not happen with Hornady brass, I'm using a Hornady full resizing die

Many thanks in advance

[Klem]

Lama,

Is this belt on the cases before or after you size them?

[Nelama]

Lama,

Is this belt on the cases before or after you size them?

After

Also tried to back up the die but the neck is not fully sized.

[Klem]

Nelama,

Quite a few of us use Lapua and do not have this problem. It might be from a hot load that fire formed the brass to the wider diameter of the bolt face. Down below the web of the case is pretty solid but brass can still flow under a lot of pressure. Then you squeezed it back to SAAMI and below the dies mouth is a tiny bit at the shell holder where it does not get sized.

The neck does not have to be fully sized - just enough to hold the bullet. Some bench rest shooters size half the neck only so it grips the bullet but also fits tightly in the chamber for accuracy. With auto loaders however you will have to full size as normal and make sure there's plenty of grip on the bullet.

If you have screwed that die in to give a .003" bump and no more, then there is nothing you can do except get a different brand of die (I use Redding and Forster). Not a huge issue but any unnecessary working of the brass reduces case life.

[Nelama]

Nelama,

Quite a few of us use Lapua and do not have this problem. It might be from a hot load that fire formed the brass to the wider diameter of the bolt face. Down below the web of the case is pretty solid but brass can still flow under a lot of pressure. Then you squeezed it back to SAAMI and below the dies mouth is a tiny bit at the shell holder where it does not get sized.

The neck does not have to be fully sized - just enough to hold the bullet. Some bench rest shooters size half the neck only so it grips the bullet but also fits tightly in the chamber for accuracy. With auto loaders however you will have to full size as normal and make sure there's plenty of grip on the bullet.

If you have screwed that die in to give a .003" bump and no more, then there is nothing you can do except get a different brand of die (I use Redding and Forster). Not a huge issue but any unnecessary working of the brass reduces case life.

Thanks for you help, I have ordered a redding die set to try , I suspect it could be the die, i'm loading N133 26.9grn with lapua 123 scenar, amazing accuracy with unfired brass, also have same hornady brass fired from the same gun but this issue does not happen.

[Old Bob]

Since it only happens on some brass, measure the case head diameters of your fired Lapua brass before you resize them. That should give you an idea which ones will exhibit that belt.

Coincidentally, the only time I experienced this was with once fired brass from Lapua 7.62x39 factory ammo. In my case, all the brass I tried to resize had the belt. None of the Remington, Winchester, Federal or PMC 7.62x39 brass from factory ammo showed the belt. I chucked the Lapua brass into my brass recycle bucket. All the ammo was fired from the same Chinese SKS...

[mtnlvr]

It feels like there's a new thread on this topic quite often.

[imaguy3]

Yea... those look identical to my post a few mths ago, however I had many more sizings on mine. I'm shooting mine in an AR platform.

I used Starline brass, BA barrel, Hornady Dies.

See my post for details, but cliff notes

-Sent brass in to starline, as well as my own I cut in half, they saw no danger or weak spots and were unable to figure out where the ring came from.

-Hornady was no help but said their die would not cause that as it's below where the die stops (I was thinking it was excess material being pushed down from sizing as my cases never really stretched to need trimming).

-BA sent me a new barrel, as I developed weird accuracy issue suddenly, they wouldn't elaborate on problem

-some recommended an adjustable gas block, theorizing it was unlocking too early. I had a midlength with H2 buffer and sandman k suppressor. I installed an adjustable gas block. It will cycle now with the suppressor but not without.

-I recently shot a few mags of my old brass that did not have the protrusion, resized, about half came out with the protrusion.

-My load is well within safe pressures.



I have new brass, eventually I'll try, I wonder if my old brass is already predisposed to do this due to the several loads prior before I changed everything. I am just waiting on my new can for this gun before I break it out and start over with load development.

I have shot several pieces with that ridge, that won't drop in but will chamber fully with pressure from the bolt, they shot fine for me

[imaguy3]

https://www.65grendel.com/forum/showthread.php?24881-Weird-wrinkle-in-brass

[lazyengineer]

It feels like there's a new thread on this topic quite often.

Yea wow. In the last few months the recurring Lapua-brass-acting-weird and occasionally Kaboom thread and it's just like.... wow.

[jasper2408]

I noticed that imaguy3 was using Starline brass and Nelama is using Lapua brass. Both are using Hornady dies. Could it be the dies or maybe the lube? Just curious. Not an expert but trying to find something common.

[lazyengineer]

I noticed that imaguy3 was using Starline brass and Nelama is using Lapua brass. Both are using Hornady dies. Could it be the dies or maybe the lube? Just curious. Not an expert but trying to find something common.

So far it seems isolated to Starline and Lapua. I think other dies get used, not sure if Hornady is the issue.

I know in .223 the casing is designed to fatige & head separate around low-mid body, leaving the base area sort of the size of a .380 casing. Leaving plenty of wall brass to still swell and seal the chamber. So broken-shells are a no-big-deal item in .223. .308 too, though those tend to break lower than I care for, leaving only maybe 1/8"? of wall to still seal, but even then, I haven't seen a .308 head spearationg cause a kaboom, even with just that.

In Grendel, in the last year people have been posting weird headspace shelf formation with Starline and Lapua brass, and only with those 2 and only in Grendel. Being premium, maybe people cycle them more and longer too, but some of the testimonials indicate still fairly young brass. The last 2(?) Kaboom posts have been head separation right the at the head itself, with insufficient wall left to stay sealed. And the gun kabooms. This is a bit unnerving, and so far appears to only be happening with brass others post this weird shelf behavior about, that's the common demoninator. And so far, only Starline and Lapua seem to be involved. Donno what the deal is, an offspec lot of brass for the premium Boys, or what? Or just coincidental is possible, since only 2 kabooms.

But I will say, if you have brass doing that shelf/belted magnum looking thing, beware.

[daved20319]

Two things come to mind, first being an out of spec or small base die. Second, you do realize you're .2 gr. over max per VV, don't you? Probably not a huge deal, especially in a bolt gun, but that's at least a pretty warm load. Any idea what the velocity is? That said, I got exactly the same thing with some .45 ACP brass and Redding dies, but that's as much as I remember, sorry. Good luck.

Dave

[tdbru]

were these starline and lapua lots, that are stretching so much, recent lots? I am hypothesizing that due to the extreme demand, that QC and process control are being marginalized in order to get as much product out the door as possible. if these stretchy starline and lapua cases are from lots produced since the demand skyrocketed, it might be that normal quality and process checks and setups are being rushed and the case head area is not at the same hardness as pre-demand spike brass. Just a hypothesis.
-tdbru

[imaguy3]

My Starline brass was from a few years back and had several firings on it.

Where the line is occurring on the brass is well below the die, Hornady said that was evidence their die had nothing to do with it.

I sectioned a case that did it, no problems or thin spots were found. I sent that sectioned case as well as a few other of my worst to starline.. he couldn't find anything unsafe about them at the time.