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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 576929 views.
stancrist

From: stancrist

23-Nov

schnuersi said:

That usually would be detrimental. Because for penetration usually the cross section density is important. This means all other things being equal a bigger diameter penetrates less. This is the case for penetration into metal.

Okay, but this armor is ceramic, not metal.  I'm thinking that the more massive SMKH core moving at 520 fps slower than the M993, is less prone to fracturing and so retains its integrity, thereby enabling it to penetrate while the lighter, blunt-nosed M993 core fragments upon impact.

Another possibility is that the ceramic was pretty much destroyed by the three 7.62 +P+ impacts, allowing the SMKH bullet to punch through part of the plate that no longer had any intact armor.

gatnerd

From: gatnerd

23-Nov

stancrist said:

1.  Why is it believed that the SMKH core is Tungsten Heavy Alloy?  Is it not documented?

SMKH appears to be a rare and poorly documented round from WW2.

Our Tungsten Heavy Alloy hypothesis is based on 3 factors

1. All the Buffman tested Tungsten Carbide cores have shattered upon encountering ceramic; even the ones that penetrated successfuly were fragmented.

However, the SMKH tests, the core has zipped through the plate almost without slowing down, the the core has punched though the clay backing, and zipped out into the countryside behind. Highly suggestive that the core is still solid and not fragmented. 

2. Adept, maker of the Colossus plate, also thought it could be a Tungsten Heavy Alloy.

3. Buffmans had tested the core, and shows a metal composition thats suggestive of WHA vs WC:

https://www.ar15.com/forums/general/WWII-German-8mm-SMKH-Vs-NIJ-Level-IV-Armor/5-2495507/

This same load was the one that killed a robust Level IV plate at 100yd:

I Did Not See That Coming!!! World War II German Ammo vs. Modern Body Armor

A big thank you to @The Mosin Crate !Test Item(s): Model 98 Sporterized, 24" barrelRounds Used:7.92x57mm (8mm Mauser), SMKH, tungsten coreArmor used: LAP...

gatnerd

From: gatnerd

23-Nov

schnuersi said:

Since THA are less hard and can be hardenend they can be machined.

Interestingly the SMKH core looks a lot more machined / elegant then the normal sintered WC cores we see, which are clearly optimized for sintering rather then ideals shape...

Vs Tungsten Carbide cores shaped for sintering:

EmericD

From: EmericD

23-Nov

stancrist said:

Perhaps the reason the SMKH penetrated the armor but the M993 failed, is simply due to the SMKH core being bigger and heavier?

Or that they (unluckily) pushed the M933 too far into the "shatter gap" zone of bullet failure against armor.

The "shatter gap" phenomenon occurs when you see a reduction of bullet penetration when the impact velocity increase.

https://www.youtube.com/watch?v=uesic33_OJM

I don't think that the M993 core was designed to withstand impact velocity above 1 km/s, but on the other hand the XM948 WC core stays intact at impact velocity above 1200 m/s.

roguetechie

From: roguetechie

23-Nov

Bulk structured materials are gonna really change the game as they get cheap enough to be used in mass production of stuff like bullets and armor.

Exciting times

JPeelen

From: JPeelen

23-Nov

Elegant looks aside, from documents at the Bundesarchiv it is clear that SmKH cores are tungsten carbide. 

We are talking of a material based on what Krupp offered on the commercial market as Widia ("wie Diamant", [hard] as diamond) for lathe cutting edges and the like.

A serious problem was that weight of the cores after sintering varied to a degree that require to sort them into weight classes. This is in my view another indication that they were too hard  for further processing to achieve a smaller weight tolerance.    

Edit: In my very limited experience with steel(!) cores it was US .20 AP M2 cores that looked smooth and elegant, while German SmK cores  showed chatter. 

  • Edited 23 November 2022 14:39  by  JPeelen
schnuersi

From: schnuersi

23-Nov

JPeelen said:

We are talking of a material based on what Krupp offered on the commercial market as Widia ("wie Diamant", [hard] as diamond) for lathe cutting edges and the like.

Right.
Its also not easily possible to tell from a picture how a part has been manufactured.

schnuersi

From: schnuersi

23-Nov

gatnerd said:

Interestingly the SMKH core looks a lot more machined / elegant then the normal sintered WC cores we see, which are clearly optimized for sintering rather then ideals shape...

It is absolutely possible to sinter such shapes. Maybe its more expensive and slower.
Its also not possible to tell from a picture what manufacturing processes the part has been exposed to.
What you think are cut marks could be all sorts of things. Maybe they ground and polished the core.
To me the marks don't really look like cut marks. They are not long and continous around the part. They are short thin lines, irregulary spread all over the part. That is very uncommon for cut marks.

The SmK(H) loading is very hot and uncompromising optimised for armor penetration. I am really not supprised that it outperfoms a modern AP loading that has cost, safety and gun longlivety critera to fullfill as well as AP performance.

My educated guess is that the better performance of the SmK(H) is due to a combination of factors. As has allready been written here.
The projectile carries more engergy, the shape of the penetrator is better for this purpose (tip will not break off) and the lower impact velocity is under the shatter threshold of the materal and shape combination. The combination of lower impact velocity combined with ~25 % more kinetic energy propably is the most important factor.

gatnerd

From: gatnerd

23-Nov

JPeelen said:

Elegant looks aside, from documents at the Bundesarchiv it is clear that SmKH cores are tungsten carbide.  We are talking of a material based on what Krupp offered on the commercial market as Widia ("wie Diamant", [hard] as diamond) for lathe cutting edges and the like.

Buffman has done a PMI (Positive Material Identification) Test on the SMKH core. 

The composition appears consistent with a Tungsten Heavy Metal composition vs Tungsten Carbide?

It's very different then M993 composition, and the armor manufacturer also believes it's some type of WHA alloy and not WC.

https://www.ar15.com/forums/Armory/Adept-Colossus-Beyond-Level-IV/10-540068/#i5795910

https://www.rembar.com/resources-technical-information-on-refractory-metals/tungsten-alloy-material-data-sheet/

As for how this mysterious super advanced AP projectile arrived in WW2, decades before WHA penetrators were fielded? I'm leaning on this:

stancrist

From: stancrist

23-Nov

gatnerd said:

Our Tungsten Heavy Alloy hypothesis is based on 3 factors

1. All the Buffman tested Tungsten Carbide cores have shattered upon encountering ceramic...

Okay, but that does not prove the SMKH core is not tungsten carbide.  There are a number of other possible explanations.

gatnerd said:

However, the SMKH tests, the core has zipped through the plate almost without slowing down, the the core has punched though the clay backing, and zipped out into the countryside behind. Highly suggestive that the core is still solid and not fragmented. 

Concur.

gatnerd said:

2. Adept, maker of the Colossus plate, also thought it could be a Tungsten Heavy Alloy.

Okay, but just because the armor maker "thought it could be" a Tungsten Heavy Alloy, does not constitute proof that it actually is.

gatnerd said:

3. Buffmans had tested the core, and shows a metal composition thats suggestive of WHA vs WC

Well, if metallurgical analysis shows the SMKH core to be WHA, then you have proper evidence and do not need a hypothesis, do you?

  • Edited 23 November 2022 22:22  by  stancrist
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