9MM Case Head Seperation

[swmass]

Hey all, had a piece of 9mm brass give out on me at the range today. Looks like just a case head seperation and not a double charge but I’m just looking for any similar experiences of insight on the situation. Load was 4.1 grains of titegroup and a 125gn round nose blue bullet. Remington 1 and 1/2 primer. Brass is nickel plated federal. Any opinions on what may cause this other than old brass? I’ve never experienced this in nearly 10,000 rounds of reloaded 9mm... the magazine was blown out of place but not totally out of the gun... gun seems fine... I check each case when loading and can pretty safely say it was not a double charge::


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[tazman]

I haven't seen anything quite like that either and it should not have happened with the load you are using.
I agree that it looks like a case failure.
Question, what pistol were you using?

[swmass]

This was out of my sig p365. It’s about a month old and I have about 200 trouble free rounds through it.

A little more info... i keep all my 9mm brass in a large container and it has come from multiple places... some old.. some new so it’s hard to tell how old that particular brass was. Looked fairly new...this just has me scared to shoot any of my other 9mm loads and I was wondering if anyone may know anything else in the reloading process that may cause this... I reloaded it just like all my other 9mm... all lee dies including lee factory crimp die.

[M-Tecs]

That is not a case head separation. It is a head failure at the unsupported area of the chamber. Normally it is caused buy on overpressure caused something like bullet setback or an overcharge. Could be an out of battery firing also but since the failure appears to match the unsupported area of some guns so it appears to be an overpressure issue. I don't have a Sig 365 but does the bulge match the chamber unsupported area?

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#5 covers this issue. https://sierrabulletsblog.com/2016/03/09/reloading-101-case-diagnostics-part-ii/

[swmass]

There are distinct burn marks on the right side of the pistol inside... I will take photos when I get home. There is a distinct burn on the right top and lower corner on the unsupported area..

[rintinglen]

That is not a case head separation. It is a head failure at the unsupported area of the chamber. Normally it is caused buy on overpressure caused something like bullet setback or an overcharge. Could be an out of battery firing also but since the failure appears to match the unsupported area of some guns so it appears to be an overpressure issue. I don't have a Sig 365 but does the bulge match the chamber unsupported area?

263555]

That was an over pressure event, at least for that casing. It may have been over worked as a result of many loadings, or the boolit may have set back on impact with the feed ramp, This case may have been "guppied" in another previous firing, then resized to iron out the bulge. But, if I had to put money on it, and you are absolutely certain it was not a double or partial over-charge, I would guess it was set-back.
in the case I witnessed, it was a 40 S&W Glock that blew out exactly as did yours. Several of the rounds in the ammo box had boolits that could be seated deeper in the case merely by pressing the cartridges against the table. Apparently. the impact of the round on the feed ramp was sufficient to drive the boolit back into the case, reducing the volume of the cylinder and greatly increasing the pressure. Those people who segregate cases by head stamp are less likely to have this sort of problem, since it reduces the probability of cases having greatly dissimilar thicknesses and neck tension.

[swmass]

These loads were only a 100 round batch, loaded right before I went to the range so it’s funny you say that. I noticed that the few nickel federal cases felt very “loose” when seating the bullet.. primer pockets felt loose as well if that makes sense... and since a double charge of titegroup would have likely blown the whole gun much worse... setback is totally possible from the loose brass and hitting the feed ramp

[onelight]

A double 4 grain charge in a 9mm case would be very hard NOT to notice so would be pretty unlikely.
Are there any more rounds in that batch that appear to be in cases that match the one that blew ? If so it might be interesting to do a press test to see if the bullets will set back then pull those down and give them a good inspection.
But it may remain a mystery .

[swmass]

It is all mixed brass and I do have a few loaded up from that batch in the same cases. I’ll have to press them onto a table and see if I get any setback.

[Lloyd Smale]

old brass can get brittle. especially old nickle plated stuff. In my experience I get about half the life out of nickle plated brass as plain brass. I tend to avoid buying it unless its real cheap. If its a blow back guy it can also be caused by not enough slide weight in a handgun or a weak spring. In an ar15 it can be caused by a to weak of a buffer spring or to light of a buffer. what happens is the brass starts ejecting to early and has still got so much pressure that without being supported by the chamber it blows out. There aren't to many blow back pistols though and its mostly a concern with ar15s.

[ioon44]

These loads were only a 100 round batch, loaded right before I went to the range so it’s funny you say that. I noticed that the few nickel federal cases felt very “loose” when seating the bullet.. primer pockets felt loose as well if that makes sense... and since a double charge of titegroup would have likely blown the whole gun much worse... setback is totally possible from the loose brass and hitting the feed ramp

Sounds like bullet set back when the bullet hit the feed ramp, if I have any thing that doesn't feel right when loading I stop and see why.
Neck tension is very important, one way I check neck tension is to put the loaded round at the edge of my loading bench and push it with my hand until my hand hurts, if you have bullet set back doing this then you need why.

[Burnt Fingers]

Range pickup brass might include 9mm major brass.

That stuff is rode hard and put away wet.

[gpidaho]

swmass: I've had the exact thing happen. It blew the magazine out of my pistol but that seems to be the extent of the damage as many rounds have been fired since. It could have been set back from not enough neck tension but I do crimp with a Lee factory crimp die. I blame it on a weak case that may have been fired in an unsupported chamber and reloaded, maybe more than once. One of the hazards of picking up range brass. Gp

[swmass]

Checked the other rounds from that batch. No setback.. I think I’ll chalk the other 75 rounds up as a loss just to be safe and keep a closer eye on my brass. I may never know what truly caused it but for now I’m going with a bad piece of brass lol

[35remington]

Run down all possible causes so there is not a reoccurrence.

The gun cannot fire out of battery so that one can be eliminated.

[swmass]

I can rule out a pure double charge. I won’t say I’m not capable of doing it... I just think 8.2 grains of titegroup would have caused much more damage... my new auto drum can vary by a few grains sometimes... I may have gotten a few more grains than expected that was just enough to blow that old piece of brass...

I did notice that all of FC nickel brass I have has been deprimed (not by me).... the gentleman who I got it from passed away and he may have been tracking that brass for some reason, as all the other brass still has a spent primer in it.

It may also be worth noting that the primers I was using are old.. the box is practically falling apart and turning to dust. Probably from the 70s judging by the design of the box. Never used them before. Doubt that would matter but hey. Here’s a picture of the head stamp. Primer doesn’t look flattened or show any pressure signs.

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[swmass]

I found this as well...

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That’s my load basically to a T. Listed 4.0 as max... if I was loading 4.1 and if the auto drum threw a few extra in there that might do it...

[gpidaho]

I thought the auto drum was going to be just the ticket for my Lee four hole turret and bought three for various turret heads. I never could get them to throw accurately with even the easy powders like TiteGroup, 231, or ball. That and two of the three leaked fine powders like a sieve. Sold them for half what I paid. Gp

[Martin Luber]

I don't know how well this chamber is supported here but if it's not, or it's glock multifires brass, then they could have been bulged too many times, just a thought. It's a scary event.

[dimaprok]

I had similar thing happen. I loaded 250 rounds pretty hot with unknown powder (CSB-1) and I tested a few beforehand for functionality but the powder thrower creeped a charge up .1 - .2 grains because I was checking periodically. Chrono'ed 1250fps out of 5.2" barrel and 1178 fps out of compact Beretta (3.8"?) Anyway, my brother's friend was shooting and it blew up but magazine was NOT blown out and was actually stuck in the chamber which I got it out but I think it broke his extractor because all subsequent rounds would not eject but could be pushed out really easy from the chamber with fingernail.

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[onelight]

Random range brass gets loaded at my house with the lightest loads that give full cycling and lock back and have reasonable accuracy for my purpose.
I use new or once fired brass that I know the history of for anywhere close to max.
I also find different powder measures/presses work better with certain powders thats why I have accumulated 4 different Kinds of measures and use them all on occasion and will not sell any of them .feed them a powder they like :-o

[swmass]

It wasn’t fun that’s for sure. I bumped the load back down to 3.9, which was my pet load for years. I was loading these hotter in order to ensure cycling in all my smaller 9mms.. the chamber is fully supported (as are all my 9mm gen 4/5 glocks for that matter...). This was just a reminder that accidents can happen even after years of reloading...Deffinetly a reminder to slow down and be more careful. I’ve got a lot of brass to go over and will be sure to keep an eye on my powder measure in the future..