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Metal Fatigue Failures: Is Your Gun at Risk

xdman said:
I have not read the article yet, but AR bolts come to mind. Thats why they should be considered a consumable item.
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I regards to that can extra BCG be purchased? What about headspace? Is that a guns smith job?
How many rounds through a AR should one start to worry about that?
 
HansGruber said:
It happens.

I had the barrel bushing on a 1911 shear the two lower “ears” off, was pretty much decided it was a metal fatigue issue.
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Was it the bushing with the 4 fingers, series 80? If so, they were prone for breakages, like the one here?

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I always kept spares of these, they would break all the time.
 
Great article. Not surprising the same thing happens in wood gun stocks.
During my years with Mossberg much of my time was spent using solid modeling to design and then have made both high speed steel and carbide tooling to produce the action cuts in bolt action gun stocks, many with rounded corners or when possible just beveled edges to help eliminate the stress risers as described in the article. Of course working with wood made the job more difficult because there was no way to predict wood grains and grain patterns until you started machining. I remember my boss asking how I can eliminate some of the cracking or stock failures. I always told him I’ve sent multiple emails to Mother Nature about the wood she makes and as of yet not received an answer. One of the biggest issues is when “floating” barrels became popular. What happens there is all the “shock” is being directed to the pads that the receiver is beaded on causing sometimes immediate stock failure. This is one of the reasons synthetic stocks have become so popular. They can handle the stress loads much better then wood.
 
Annihilator said:
Was it the bushing with the 4 fingers, series 80? If so, they were prone for breakages, like the one here?

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I always kept spares of these, they would break all the time.
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Nope; it was a standard GI style on a Norinco.

A few folks knowledgeable in metallurgy looked at it, said it appeared there was a stress fracture on one of the ears, and the other let go when the first sheared...possibly one sheared first, then the second let go a few shots later. But one side appeared “torn”, which was the second one, most likely.

Replaced it with a Ed Brown bushing and didn’t worry about it....and I now mainly use it as a .22 with a Kimber conversion slide.
 
HansGruber said:
Nope; it was a standard GI style on a Norinco.

A few folks knowledgeable in metallurgy looked at it, said it appeared there was a stress fracture on one of the ears, and the other let go when the first sheared...possibly one sheared first, then the second let go a few shots later. But one side appeared “torn”, which was the second one, most likely.

Replaced it with a Ed Brown bushing and didn’t worry about it....and I now mainly use it as a .22 with a Kimber conversion slide.
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Wasn’t the Norinco’s made in China?
 
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