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Old December 4, 2013, 03:47 PM   #1
TPD211
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Case Separation

Shooting my Mechtech Glock 40 S&W Carbine today I had a case separation.

Another round loaded into the separated case in the chamber when the bolt cycled.

The Mechtech suffered no damage from what I could tell.
It functioned and cycled fine after the separation.

It was probably an overcharged reload that did it.

That's a first for me.

Mechtech & Charter Arms 40 S&W Revolver


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Old December 4, 2013, 04:43 PM   #2
Chaz88
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That looks like a really heavy crimp. Could that be the problem?
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Old December 5, 2013, 10:25 PM   #3
barnbwt
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At least you got a free broken shell extractor out of the deal . No, no, wait; at least you got some Nagant revolver-style silencer ammo for your Charter Arms out of the deal .

I take it no signs of stretch/bulging on the other fired cases (I forget if the MechTech is a straight conversion or a blowback). It's also possible, if not likely, that the case separated under bolt momentum during extraction on the stuck shell, rather than a pressurized rupture out of battery. I think the latter would have been rather noticeable . Heavy crimp can raise pressures and cause brass to stick more, hence tearing more often upon extraction. However, a healthy crimp isn't exactly a bad thing for 40SW since bullet setback can be just as dangerous (in a heavy-bolted blowback, perhaps moreso)

Good thing that next round jammed, right?

TCB
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Old December 5, 2013, 11:36 PM   #4
James K
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It isn't 10000% but case separation is almost always a result of excess headspace. Rarely, it can be a result of some other kind of loss of case support.

Jim
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Old December 6, 2013, 06:58 AM   #5
Mobuck
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With that crimp on a case that headspaces on the case mouth, I'm surprised it even fired. Maybe need to read reloading manual again.
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Old December 6, 2013, 08:03 AM   #6
mete
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What kind of die are you using ?? There are two parts to hold the bullet -grip on the case , and crimp .The grip on the case should be enough so that holding it in your hand and pushing the bullet with your thumb you can't move the bullet .For autos a TAPER crimp die is used, and for revolvers a standard crimp die is used.Too little crimp prevents proper ignition of the powder and too much can reduce accuracy.Autos headspace on the rim and it looks like your ammo too much crimp is preventing proper headspace !!
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Old January 12, 2014, 06:10 PM   #7
TPD211
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Quote:
With that crimp on a case that headspaces on the case mouth, I'm surprised it even fired. Maybe need to read reloading manual again.
OH MY GOSH.... WHY DIDN'T I THINK OF THAT.......

Seriously.... Whats a reloading manual???????

Anyways, yup, the crimp was my fault. I see that even without reading the manual again....

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Old January 14, 2014, 06:44 PM   #8
chris in va
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Aside from the malf, how do you like that upper? Had I kept my G21, probably would have bought one.
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Old January 14, 2014, 07:21 PM   #9
Bart Noir
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Now that I have a Glock 20, I ask the same question as Chris.

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