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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 555262 views.
gatnerd

From: gatnerd

25/11/19

"The pic you posted earlier looks like an exact copy of the 130gr Classic Hunter (Part # 27570) shown in the Berger chart below."

That does look very similar. 

There's also the question of - how much weight do we give an image in the power point presentation? Is it the surrogate, or just a handy image they grabbed?

A more reliable but more difficult to gauge metric would be examining the shown projectiles used in the 6.8 prototypes.

Right now, my 140gr hunch is based on the 6.8 Cobalt/Mars - it seems odd that they'd be advertising a 140gr @ 3200fps if the Surrogate was a 130gr.

 

"Great find!"  

Thanks! Yeah, I was really tickled when i stumbled across that image in the TFB comments. It was really a stroke of luck / late night internet madness.

 

"I wonder if the "GP" and "SP" nomenclature are just for use during development, or will they replace the traditional "Ball" and "AP" terms if the NGSW enters service?"

Hard to say. I hope they do though.

"Ball" doesn't really do the EPR justice. Its a 2/3 AP projectile that also fragments - which really is a wonderful, 'General Purpose' projectile design. 

And since the EPR - especially this really nasty long 6.8 EPR - has ~comparable penetration to historical AP rounds, I also like 'Special Purpose' as a descriptor for the specialist, extra AP Tungsten projectile. 

 

gatnerd

From: gatnerd

25/11/19

"Maybe, but both the 130 grs & 140 grs from Berger are too short (1.24" and 1.274" respectively) compared with the estimated ~1.40" of the EPR bullet. On the other hand, that could explain the comments of some competitors..."

Yes, the comments definitely suggest the EPR 'GP' is longer then the Surrogate. And of course, if the Surrogate = 6.8 EPR, then there would be no point in the Surrogate for developing the cartridge. 

And if we're talking about a Tungsten 'SP' round, I imagine it would have to be shorter then the 6.8 GP, due to WC being 2x as dense as steel, if the projectile is to remain a comparable weight. 

For example, the Penetrator weight of the M80A1 is 44gr. Same exact size in WC would be 88gr - so a Tungsten M80A1 EPR would weigh 174gr. The result would be a dramatically different velocity from the 130gr original.  

Perhaps maybe a Tungsten core base with polymer tip to lengthen the ogive an mimic the shape of the 6.8 GP? Or replacing the copper base with aluminum? 

 

stancrist

From: stancrist

25/11/19

gatnerd said...

"The pic you posted earlier looks like an exact copy of the 130gr Classic Hunter (Part # 27570) shown in the Berger chart below."

That does look very similar. 

There's also the question of - how much weight do we give an image in the power point presentation? Is it the surrogate, or just a handy image they grabbed?

Good question.  It wouldn't be the first time that a "handy image" was used in one of these presentations.

 

gatnerd said...

A more reliable but more difficult to gauge metric would be examining the shown projectiles used in the 6.8 prototypes.

Left, below:  .270 WSM w/140gr Berger Classic Hunter.  Right, below:  SIG 6.8 NGSW.  Does not look like a Berger bullet to me. 

The ogive looks different, and the tip smaller and more uniform.  Also, it looks like a copper solid, not a jacketed lead-core bullet

Image result for berger .270 cal 140gr classic hunterImage result for ngsw ammo

 

gatnerd said...

Right now, my 140gr hunch is based on the 6.8 Cobalt/Mars - it seems odd that they'd be advertising a 140gr @ 3200fps if the Surrogate was a 130gr.

Well, it also seems odd that the pictured Cobalt/MARS round has what looks very much like a 130gr Barnes TTSX bullet, instead of the BTHP projectile seen in the other 6.8 cartridges.

                                                                            Image result for barnes .277 130gr ttsx bullet

Image result for ngsw ammo

  • Edited 25 November 2019 22:16  by  stancrist
gatnerd

From: gatnerd

26/11/19

"

Good question.  It wouldn't be the first time that a "handy image" was used in one of these presentations.

Left, below:  .270 WSM w/140gr Berger Classic Hunter.  Right, below:  SIG 6.8 NGSW.  Does not look like a Berger bullet to me. 

The ogive looks different, and the tip smaller and more uniform.  Also, it looks like a copper solid, not a jacketed lead-core bullet

Well, it also seems odd that the pictured Cobalt/MARS round has what looks very much like a 130gr Barnes TTSX bullet, instead of the BTHP projectile seen in the other 6.8 cartridges."

Yes, it seems like we have too many speculative data points to really declare the Surrogate any particular projectile or weight with any certainty.

 

So far what we know:

6.8 General Purpose = ~125-135gr Steel Tip EPR with an aggressive, VLD design, ~1.4"/35.5mm long

6.8 Surrogate = Unknown weight projectile. Per design questions, surrogate has a shorter ogive then the GP. And Surrogate is a stand in for a future 'Combat Projectile' that is not the GP, so likely some sort of Tungsten AP load. 

6.8 Special Purpose = Tungsten AP load. Uses "lessons learned" from Tungsten EPR ADVAP XM1158 7.62 projectile, but not guaranteed to be an Tungsten EPR. Per Army comments, projectile may continue to evolve. 

 

As to the 6.8 SP, I'm increasingly less inclined to believe it will be a Tungsten Tip EPR. 

We don't have a model of the 6.8 GP EPR, but we do have Nathaniel's very similar '6.86 Romulan' 125gr EPR:

https://www.thefirearmblog.com/blog/2017/09/09/romulan-vulcan-preference-driven-vs-process-driven-design-field-small-arms-ammunition/

.277 125gr 

jacket + slug = 88.625gr

Slug = 56.675gr

Steel penetrator = 36.375gr

 

s7 tool steel = 7.83g / cm3

Tungsten carbide = 15.63g

-->

WC penetrator = 77.61gr

-->

6.8 Tungsten EPR = 161gr

Since the goal of the 6.8 NGSW is between 2850-3200fps, that would seem to negate the chances for a 161gr 6.8 projectile. 

On the other hand, EPR may be possible with a different base material then copper. Replacing the copper slug with Aluminum would shave off 39.286gr

--> 6.8 Tungsten / Aluminum EPR = 122gr

 

However that then gets back to the problem of the Surrogate. If they were going to use the same 6.8 GP projectile form factor and weight for the Tungsten SP, there would be no need for a surrogate. And since the surrogate is apparently shorter ogive then the 6.8 GP, then it seems the SP will be a different design. 

So we're back to the mystery wagon on what the final SP will be. All we know is that it will be a tungsten something in 6.8. 

nincomp

From: nincomp

26/11/19

How densely can tungsten powder be packed?  It is conceivable that the mass and form factor of the eventual AP projectile could be replicated by a copper jacket filled with packed tungsten powder.  Although it would be expensive, this would allow some data to be collected prior to the availability of the final product.  I have some doubt, though, that the US Military would want a light EPR and a heavy AP projectile in a weapon designed for long range accuracy unless they are committed to sights that can automatically switch between the two.

Of course the silly side of me thought that DU or gold could be used to achieve the correct density.  The DU-filled bullets would of course be tested at a nuclear waste facility to contain the dust and the gold-filled ones tested inside an active gold mine to facilitate recovery.   I would never mention such ideas in a serious forum like this one, however!  ;)

gatnerd

From: gatnerd

26/11/19

"How densely can tungsten powder be packed?  It is conceivable that the mass and form factor of the eventual AP projectile could be replicated by a copper jacket filled with packed tungsten powder.  Although it would be expensive, this would allow some data to be collected prior to the availability of the final product."  

Thats possible, although I imagine most of the design is done with computer modeling. Things like SolidWorks have complete densities of various materials, so the computer can tell you quite accurately what will a simulated projectile would weight. 

 

"I have some doubt, though, that the US Military would want a light EPR and a heavy AP projectile in a weapon designed for long range accuracy unless they are committed to sights that can automatically switch between the two."

Yes, I don't think they would go for a heavy AP projectile either. If you look at the earlier Nammo data I posted, the 168gr AP at 2650fps penetrates 18mm RHA at only 80m vs 100m for the 130gr @ 3050fps. So velocity is clearly a factor.

nincomp

From: nincomp

26/11/19

gatnerd said...

"How densely can tungsten powder be packed?  It is conceivable that the mass and form factor of the eventual AP projectile could be replicated by a copper jacket filled with packed tungsten powder.  Although it would be expensive, this would allow some data to be collected prior to the availability of the final product."  

Thats possible, although I imagine most of the design is done with computer modeling. Things like SolidWorks have complete densities of various materials, so the computer can tell you quite accurately what will a simulated projectile would weight. 

I agree that is is easy to determine the weight of a projectile.  The issue is that the final product would likely not be available for the design and initial testing of the weapons.  I was simply thinking that the core of the surrogate would need to be heavier than lead to match the weight and form factor of a projectile that contains a significant amount of tungsten.  This way the designers could do some physical testing in conditions (mud, dust, extreme temps) that are difficult to model.  I would think that correctly replicating the weight and form factor would be particularly important since the vendors are developing the cartridges from the ground up, including choosing a propellant.  They would want to confirm the effects of extreme conditions on all components of the cartridge and the interface of the cartridge and the weapon.

  • Edited 26 November 2019 14:01  by  nincomp
gatnerd

From: gatnerd

27/11/19

"I agree that is is easy to determine the weight of a projectile.  The issue is that the final product would likely not be available for the design and initial testing of the weapons.  I was simply thinking that the core of the surrogate would need to be heavier than lead to match the weight and form factor of a projectile that contains a significant amount of tungsten.  This way the designers could do some physical testing in conditions (mud, dust, extreme temps) that are difficult to model.  I would think that correctly replicating the weight and form factor would be particularly important since the vendors are developing the cartridges from the ground up, including choosing a propellant.  They would want to confirm the effects of extreme conditions on all components of the cartridge and the interface of the cartridge and the weapon."

Well what's interesting is that despite WC being very heavy (15.63g/cm3 vs 11.34 for lead), we never see any of the AP WC projectiles being heavier then their lead counterparts.

The reason I believe is the sizing of the WC cores. Because WC is sintered, it typically has to be formed in a pretty basic shape that tends to produce pockets of hollow space inside the projectile:

So while lead is 72.55% the density of Tungsten, we see these WC cores to not typically fill 100% of the interior space of the bullet, leaving a fair bit of air. 

As such, 1x FMJ w/ 100% lead fill = 1x FMJ w/ ~72 % WC fill in weight.   

So for a practical standpoint, its likely possible to make a lead VLD surrogate nearly identical in weight to the Tungsten VLD projectile its intended to simulate. 

 

ZailC

From: ZailC

27/11/19

gatnerd wrote: The reason I believe is the sizing of the WC cores. Because WC is sintered, it typically has to be formed in a pretty basic shape that tends to produce pockets of hollow space inside the projectile 

Not your old backyard sintering, no more voids from reputable manufacturers. Touches of iron, nickel, and molybdenum (sometimes) in the mix. Near-net shape sinter core is fused in high-pressure hydrogen (HIPPED) and roller wrought to 99+% density. Hardness to Rockwell 64 if well done. 

gatnerd

From: gatnerd

27/11/19

"gatnerd wrote: The reason I believe is the sizing of the WC cores. Because WC is sintered, it typically has to be formed in a pretty basic shape that tends to produce pockets of hollow space inside the projectile 

Not your old backyard sintering, no more voids from reputable manufacturers. Touches of iron, nickel, and molybdenum (sometimes) in the mix. Near-net shape sinter core is fused in high-pressure hydrogen (HIPPED) and roller wrought to 99+% density. Hardness to Rockwell 64 if well done."

I should have been more precise in my writing. I didn't mean that there are air pockets in the WC sintered core itself. 

Rather, the shapes used in the cores do not typically occupy 100% of the interior volume of the jacketed projectile, leaving some pockets of air inside the jacketed projectile. And so a Jacketed projectile 100% filled with lead will be comparable in weight to a Jacketed WC round where the WC occupies only ~75% of the interior space. 

This can be seen in the pics of the sectioned AP rounds.

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