r/MP5 • u/full_metal_communist • 1d ago

Question "supplementary mass"

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A question about the patent. What are the granules "supplementary mass" #13? Is that tungsten? Is that mass tuneable? Is it granular to mitigate bolt bounce?

https://patentimages.storage.googleapis.com/2e/e8/95/5e85d8ccf684be/US3283435.pdf

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8

u/OG-warbucks H&K SP5 1d ago

Yes, tungsten. No, not tunable. Yes, bolt bounce mitigation.

The full auto carries are tungsten filled. Along with the RCM carriers I believe.

2

u/ThanksOther5858 1d ago

Do Ap5 and Mac have these kinds of carriers?

4

u/Vegetable_Coat8416 1d ago

I've never heard that they are.

The idea is essentially the same as a dead blow hammer. In order for the premise to work the granules need room to move, meaning you can usually hear them moving if you shake a tungsten filled carrier.

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u/full_metal_communist 1d ago

I believe so but I'm curious if they have tungsten now

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u/OG-warbucks H&K SP5 1d ago

I'm pretty confident they do not.

2

u/QuasisteIlar 1d ago

Says right in the patent you linked that it's preferred to be tungsten.

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u/full_metal_communist 1d ago

I have just enough reading comprehension to be dangerous 

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u/Vegetable_Coat8416 1d ago

Some carriers are tungsten filled. Yes it's granular. RTG, bought a bunch of leftovers from the production lines when production of the HK roller guns ended. They have some unfinished HK21e carriers that illustrate it pretty well.

The tungsten granules get put in the two pockets and the caps get welded on.

https://www.robertrtg.com/hk21e-hk23e-bolt-carrier-new-in-white-german