Why rifle safety features are important - AI-AW50

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Just to fuel my curiosity, what is the date headstamp? Hard to tell, but it looks like "32", or is that an "82" (...or something else altogether)?

:)
 
Figured that much, '32 would be some mighty old .50BMG (though I have an old WWII AP round from 1943). Thank you for satisfying my curiosity.

:)
 
Not to be a dick, but why is your eye protection on your forehead?

Sure, they look cool up there but they certainly can't protect your eyes from that position.

BSW
 
Not to be a dick, but why is your eye protection on your forehead?

Sure, they look cool up there but they certainly can't protect your eyes from that position.

BSW
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I assure you that he's not about to fire that weapon.

You'd be hard pressed to find a photographer sufficiently obtuse to sit at that angle from a .50 BMG muzzle brake...
 
Not to be a dick, but why is your eye protection on your forehead?

Sure, they look cool up there but they certainly can't protect your eyes from that position.
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My eye protection was right where it needs to be - in front of my eyes. I wear eyepro 100% of time. You'll have to find the guy in the photo and ask him yourself; I can't answer for him.
 
You'd be hard pressed to find a photographer sufficiently obtuse to sit at that angle from a .50 BMG muzzle brake...
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Well, not twice, anyway. I wasn't thinking about the angle...

I'm just sensitive about wearing eye protection as I've worked with a couple of people that were blind in one eye as the result of trauma.

We recently had a guy at a match get a fragment of rock in his lower eyelid from a berm hit. He was wearing his safety glasses and the rock fragment came in under the edge of the lens.

People often ask me (usually during the summer) if the goggles aren't hot. They are, but I like the full protection. BSW

IMG_5966Medium.jpg
 
Here's the case head for comparison

D463_4892_img.jpg

This load is way under max so in conjunction with the head condition it is unlikely it was overpressure. My money is on freak case defect.
 
Zak Smith said:
This load is way under max so in conjunction with the head condition it is unlikely it was overpressure. My money is on freak case defect.
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There isn't much comfort in that since it's impossible to predict or control "freak case defects" but AI has you covered (right?). A point defect would have to be a crack, pit (from corrosion) or inclusion but without further analysis you'll never know. Let me know if you want additional analysis done (no charge) using SEM and EDXA techniques. Regardless, it clearly isn't a case head separation issue so the question is, are you going to continue to use that lot of cases?

:)
 
luckily, i just got my eyeballs recalibrated by the national standards institute (ANSI). my highly scientific observation (NOT) is the primer shows no signs of excess pressure. i'd be prone to roll with you ~and~ 1858. bad case, delete same lot brass.

gunnie
 
One other general note is that the case wall thickness on the end part we cut off is approx 0.015" different from thick side to thin side, but the crack was not on the thin side-- it was halfway between the two.

1858,

No kidding. Impossible to predict case defects are kind of scary once you start to think about them! I'd love to get to the bottom of what caused the problem - please email or PM me privately and I'll mail you the cut-off case head.

1858 & gunnie,

I have a bunch more brass and the 82-83 LC is the minority, so I am planning to simply not use that brass anymore. I do have some more recent LC, some IMI, and some Barrett, so the question now is: Do I shoot even the more recent LC, or just stick with the IMI and Barrett brass that I know was not fired in machineguns?

-z
 
Do I shoot even the more recent LC, or just stick with the IMI and Barrett brass that I know was not fired in machineguns?
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Take this with a grain of salt, because I haven't a .50BMG, and my experience with one is limited, but understanding the stresses that the brass undergoes when fired from a M2 I would feel more secure with the IMI/Barrett stock that you have.

:)
 
On the other hand LC brass is used extensively for all manner of .50 loads that are going to be shot in bolt guns, and reports of this type of event are very rare.
 
Dang...didn't expect the case to be that thick.


Good to know some engineers somewhere thought of those rifle safety features though...


Good example of why one should always wear eye protection. Not all actions handle escaped gas that well.
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+1




Beautiful rifles btw Zak.
 
On the other hand LC brass is used extensively for all manner of .50 loads that are going to be shot in bolt guns, and reports of this type of event are very rare.
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Have to agree with that too, you are unlikely to ever repeat the event, but why tempt fate? I would use what I had (excepting this lot), and use brass of known origin (not MG brass) henceforward.

Good to know some engineers somewhere thought of those rifle safety features though...
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Speaking of which, this thread is like an AISC convention, failures are like Engineer attractant.

:)
 
In my real job I am a verification engineer, which - I half-joke to my wife - is about asking inappropriate questions to see what answers I get.
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Hmm, suppose I just assumed that you were an ME, due to your suppressor business. We won't hold too much against you. :p
 
Zak Smith said:
1858, No kidding. Impossible to predict case defects are kind of scary once you start to think about them! I'd love to get to the bottom of what caused the problem - please email or PM me privately and I'll mail you the cut-off case head.
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Zak, I just sent you a PM with my address. As I mentioned in the PM, I won't post the results but rather, I'll send you the data (images and spectra) and you can interpret and use the results in any way that you see fit.

As for the LC brass (both lots) ... hmmm ... I'd use it to make .50 cal windchimes and sell them on Ebay or load them up with a "pretty" bullet, no powder and a fake primer and use them as stocking stuffers!! Seriously though, how much LC brass do you have compared to the IMI and Barrett cases?


Zak Smith said:
One other general note is that the case wall thickness on the end part we cut off is approx 0.015" different from thick side to thin side, but the crack was not on the thin side-- it was halfway between the two.
Click to expand...

You mentioned that this sort of failure is unusual but you also mentioned that there was a difference in case wall thickness. I use a Redding Case Neck Gauge to measure case neck wall thicknesses. The theory is that an inconsistent neck wall thickness is indicative of inconsistent wall thickness througout the whole case. It would be interesting if you compared the LC brass to the Barrett or IMI using a similar tool. Redding recommends < 0.001" runout during one full rotation of the case neck.

redding_neck_good.jpg


redding_neck_bad.jpg


:)
 
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