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Bullet tumbling


JohnnyDog
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I work for an ammunition manufacturer, so I can't get into specifics.We recently purchased a batch of 180 gr 40 cal JHP projectiles from a new supplier. We assembled the ammo and sent it out to our customer, who is a law enforcement agency. The ammo was fired from several different weapons, and they returned the lot because of severe tumbling issues. We've produced a couple million rounds in the past and this was NEVER an issue. From all the info that I've gathered, the consensus is that the crimp is too tight for this particular suppliers projectiles. What I did today was to make certain that the crimp was not too tight, and made 10 rounds using the projectiles that we've used in the past, and 10 from the new supplier. All 20 rounds were made to the same exact specs according to our ballistic recipe. We cleaned the weapon, and then loaded each set of 10 rounds into 2 separate magazines. We warmed the barrel by firing 5 rounds from it before we conducted our test. The 10 rounds that we fired from the old supplier did not tumble, The 10 we fired from the new supplier had 4 out of 10 tumble. We are ABSOLUTELY CERTAIN that it is not a crimp issue. Any thoughts.

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1 hour ago, JohnnyDog said:

We are a relatively new company, (in business less than 3 years), without a ballistics lab. We are learning as we go, and this is a new issue. We will go back to our old manufacturer, but we are curious as to the cause of this issue. 

Were the old bullets plated ? Are the new bullets plated? 

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I speculate the new bullets are harder and are not obturating on firing and thus not getting stabilized. You could try a faster powder to see if it works but do not go overpressure as 40 is a bit tricky in hoop strength.

Edited by Solvability
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It does not seem an odd place to find guidance for ballistic problems.

I'd go down the list of usual causes of tumbling.

leading causes are already mentioned and the firearm causes are off the list

 

As you have a clear cause in 'new' bullets, check dimensions. 

 

as far as a "lab" goes,  your company has one...

 

miranda

 

 

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