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Chief Rick

USMC Polymer .50 BMG cartridges

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Lets see just  how well the 'plastic' holds up in a hot chamber..........:rolleyes:

OLG

 

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I have fired the military experimental polymer cased rounds in 9mm, 223, 6.5, and 308.  Not the 50 yet. The cases have brass bases.

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35 minutes ago, Happy Jack, SASS #20451 said:

I have fired the military experimental polymer cased rounds in 9mm, 223, 6.5, and 308.  Not the 50 yet. The cases have brass bases.

How did the 223 or 308 deal with heat after sit'n in a hot chamber for a spell?

Did you fire these in automatic weapons?

OLG

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2 minutes ago, The Original Lumpy Gritz said:

How did the 223 or 308 deal with heat after sit'n in a hot chamber for a spell?

Did you fire these in automatic weapons?

OLG

The Hi-Tek polymer coating on bullets does not burn or melt when a coated bullet is dropped into a pot of hot lead. It just sits there till the lead heats up and causes the coating to crack due to the thermal expansion of the lead.  

 

Done right the polymers can be as tough as steel.

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11 minutes ago, Sedalia Dave said:

The Hi-Tek polymer coating on bullets does not burn or melt when a coated bullet is dropped into a pot of hot lead. It just sits there till the lead heats up and causes the coating to crack due to the thermal expansion of the lead.  

 

Done right the polymers can be as tough as steel.

Agree on the bullet coating. I have shot lots of poly-coated bullets over the years.

Still-A polymer case, is a whole new deal. Even with a brass case head.

OLG

 

 

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Lumpy, ran the 223 full auto with no problems but didn't let one sit in the chamber for more than a minute. Seemed OK. The 308 only ran semi but it also performed fine.  Polymer is slower to transfer heat than brass so powder should heat up slower. I can see the weight savings on something like a 50, but it is still a crew weapon so not sure about the actual improvement in the field. I still feel the best use is subsonic as the case walls can be thick and get a good powder fill with the low charge weights.

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4 minutes ago, Happy Jack, SASS #20451 said:

Lumpy, ran the 223 full auto with no problems but didn't let one sit in the chamber for more than a minute. Seemed OK. The 308 only ran semi but it also performed fine.  Polymer is slower to transfer heat than brass so powder should heat up slower. I can see the weight savings on something like a 50, but it is still a crew weapon so not sure about the actual improvement in the field. I still feel the best use is subsonic as the case walls can be thick and get a good powder fill with the low charge weights.

Exactly. Nobody is humping cans of 50 ammo.

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Helicopters still run the 50 for defense.

Less weight could mean more ammo carried. 

OLG

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7 minutes ago, The Original Lumpy Gritz said:

Helicopters still run the 50 for defense.

Less weight could mean more ammo carried. 

OLG

 

...and fuel economy in air and ground vehicles - :D :P

 

GG ~ :FlagAm:

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Lighter is better if it works reliability.    I wonder what the cost difference is?  Should be cheaper, but not likely.

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2 hours ago, Badlands Bob #61228 said:

Lighter is better if it works reliability.    I wonder what the cost difference is?  Should be cheaper, but not likely.

Article didn't list costs but...

 

MAC LLC, a company out of Bay Saint Louis, Mississippi, is the company that will likely receive the sole source contract unless another company can show they meet the requirements and can do a better job before the federal deadline in a couple of weeks to deliver an estimated quantity of 2.4 million cartridges for the Corps over three years.

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Besides the weight savings the polymer cases cannot be salvaged and used by our enemies to be reloaded or melted down to make other cartridge cases .  IIRC this was one of the big selling points for polymer cases.

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I have fired 556 and 7.62  and  the cases come out mildly warm but no way would you call them hot

that said one would think chambers will run cooler

so “cook offs” seem less likely

556 and 762 military ammo is being sourced from a firm here in Texas not sure about the 50 though

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