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Old January 21, 2013, 11:30 PM   #1
j357
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Diagnose Split .357 Mag Case

I loaded up some light .357 Magnums a few months back and had a chance to shoot them today. Near the end of the box I had one set of six cases that did not easily drop from the cylinder. Found a split case that concerns me. I suspect it was a bad case, I just can't figure out what happened outside that.
Details:
Mixed .357 head stamp all nickle plated. Split case is a Federal, and had 6 more in the box that show no problems. 125 grain Semi-jacketed FP, CCI 500 primers, loaded with 6.6 grains of Clays Universal - Lee powder measure on at LCT press, firm crimp on the groove. All shot in a SW Mod 28 which shows no sign of problems or damage. Subject round produced no noticeable difference in recoil. Pictures attached.

Any insight on what could have caused this would be appreciated.

EDIT: 6.6 grains Universal is well below the general minimum load I could find from several sources = 7.0 was the starting load number I located, but figured I would even drop back from that.
Attached Images
File Type: jpg 357primer.jpg (88.9 KB, 141 views)
File Type: jpg 357side.jpg (97.5 KB, 151 views)

Last edited by j357; January 21, 2013 at 11:46 PM.
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Old January 21, 2013, 11:34 PM   #2
jimbob86
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I've had them split, but never that bad....

Quote:
Mixed .357 head stamp all nickle plated.
All of the cases I've had split at the neck were also nickel plated.
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Old January 21, 2013, 11:41 PM   #3
chiefr
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I too have never seen one split like that, even with hot reloads.
I have seen more 357 splits than any other handgun cartridges. I do not know why. Of all the 357 splits I have seen, 95% or more were nickel plated. Other splits I have encountered are with 38SPL+P. Never could isolate splits to one brand, they all do it.
IMHO, the case walls are too thin for the pressures.
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Old January 22, 2013, 03:22 PM   #4
schmellba99
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Looks like it was a bad piece of brass to me with how the split almost went to the rim of the case.

Could have been just a bad piece that would have split anyway, but also could have been exaggerated with the below starting load you loaded with.

Pistol powder burns fast - dropping below starting loads can lead to excessive pressures in your chamber due to the fast burning powder and the increased air space you allowed with the lower starting load. I'm not saying it is the cause, but it could very well be a contributing factor. I wouldn't drop below published loads just like I wouldn't start out going above max published loads.
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Old January 22, 2013, 03:50 PM   #5
Sevens
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That's definitely a light load of Universal under a 125 grain bullet. I will also agree that this particular split seems excessive, and will also very much agree that nickel plated revolver brass simply DOES split, and at a rate much, much, much higher than non-nickel traditional brass cases.

I am no expert. But in your position, I would keep an eye on your brass, especially your nickel plated brass and see if the problem repeats itself.

At this point, with the sheer number of split (nickel!) pieces of revolver brass I've experienced, I simply wouldn't worry all too much about it.
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Old January 22, 2013, 04:05 PM   #6
mete
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I'd like to see that case close up. How many rounds through the case ? The direction of the crack is a bit strange .
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Old January 22, 2013, 04:47 PM   #7
mehavey
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Quote:
Mixed .357 head stamp all nickle plated
There is your problem. Nickel-plated cases are designed to reduce corrosion in the exposed belt-loops
of a LEO's leather rig and/or in tropical climate. Unfortunately the nickel plating also causes significant
accelerated brittleness in an otherwise ductile brass case.

Google < nickel plated brass case brittle > and see what I mean
I wish I could tell you otherwise ...........

Last edited by mehavey; January 22, 2013 at 08:39 PM.
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Old January 22, 2013, 04:57 PM   #8
BigD_in_FL
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Quote:
EDIT: 6.6 grains Universal is well below the general minimum load I could find from several sources = 7.0 was the starting load number I located, but figured I would even drop back from that.
Shooting too light a load can also cause problems. There have been countless threads about this causing KBs in guns
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Old January 22, 2013, 08:58 PM   #9
mehavey
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6.6gr Universal (which for all intents/purposes ~ spheroid Unique) should not cause any problems.**
If I calibrate QuickLoad to Speer's 125gr UCHP for 7.5gr Universal in velocity predicted -- and then
drop the charge to 6.6gr -- QL predicts 15,300psi and 1,044fps (barrel friction included) out of a 5" barrel.

Pretty nominal mouse load for a 357Mag.

This is just a case (no pun intended) of very brittle nickel-plated brass.



** It's the hi-energy/spherical/hard-to-ignite powders like W296/H110 that (potentially) get you in trouble if case-fill ratios fall too low. In Universal's case, Hodgdon lists as low as 4.8gr for 125gr cast bullets. So ignition predictability isn't much of an issue. (Note that if I ratchet the volume-calibrated QL load up to 7.1gr Universal, it also matches the Hodgdon cast data, so I feel pretty comfortable w/ the results above)

Last edited by mehavey; January 22, 2013 at 09:10 PM.
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Old January 22, 2013, 09:30 PM   #10
GP100man
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The process used to get the plating to stik to the brass has bad affects on it`s ductilability (is that a real word ??) & thus shortens it`s service life compared to plain yellow brass, generally.

With that said I`ve shotfactory loadings from all the major suppliers in the past loaded in yellow brass thathave split on the initial firing !

& I have loaded nickel cases until the nickel wore thin & also have had the plating to flake off .

In general I don`t seek nickel cases to load ,but yes I do have some loaded , they`re in the loops on the belt .

Glad you or the revolverwere`nt hurt !!!

I have been known to anneal yellow 357 brass!



They went rite back to shooting very consistently across the chrony!!
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Old January 22, 2013, 11:00 PM   #11
j357
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Thank You to everyone for responses and input!

Now on to answering some questions that have come up, some of which I should have addressed to begin with.

@ mehavey - Thanks for the QL insight, confirms my general research in several manuals that my load was most likely not too light for the case (even though it was very light). Many people advocate loading .38 Spl levels in .357 Mag cases. I went for greater than .38+P and less than .357 by a very educated estimate. ALSO if you could rerun the numbers based on a 6 inch barrel I would appreciate it, as that’s what my Mod 28 is.

@mete - many of these cases have been hanging around my bench around 15 years now that I think about it. I would imagine some are range pick up. All were carefully inspected and showed no sign of head stamp smear or primer flattening when I processed them. None showed flaking or thinning of the plating. I would assume less than 3 or 4 loadings on those that may be used pickup, if that. I had not previously reloaded any of these personally.

FWIW, After some searching, I find a lot more concern with nickel plated brass than reduced loaded .357s. However, I will visit the Lee reduced load manual section at this point.
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Old January 22, 2013, 11:36 PM   #12
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One of the great things about revolvers is when the case splits it doesn't hurt anything.
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Old January 23, 2013, 09:48 AM   #13
L_Killkenny
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Couple thoughts here....... Someone correct me if I'm going the wrong direction.

I've had half dozen cases split pretty similar with light loads in .32 H&R. FTR, cases were Starline brass, load is 2.0 grs TiteGroup behind a 98gr RNFP. I had always figured it was brittle brass that may need some annealing until I realized I never had issue with medium loads on up. Too the best of my knowledge it appears to be a combination of low pressure and "slightly" brittle brass not allowing for proper expansion of the case.

Now I'm not sure how you're Universal load compares to my load in burn rate or pressure but can tell you mine is basically a .32 long load in H&R cases. Never the less, I wouldn't worry about one, you start seeing em consistently and I'd either anneal or toss the cases.
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Old January 23, 2013, 10:21 PM   #14
SHR970
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Looks like there was a weak spot near the head which propagated to the neck. When I blow the picture up it looks like there is a dark region near the head which would be the site of the original failure. Since the case head is the thickest part, the failure went away from it going via the path of least resistance. That is in the direction of the case neck.

I've had this happen before in non-nickeled brass with the failure point being in the center of the brass. In one case the site was obvious since the split had an unusual feature which was the obvious failure location.

Looks like a case of a bad draw forming the brass.
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Old January 24, 2013, 11:53 AM   #15
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x2 with the others - the more a case is worked, over time the brass can simply lose it's ductility. it is possible that your load was fine, and the brass had finally worked it's way to where it couldn't stretch anymore. it simply got work hardened and brittle - and shattered.
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