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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 132658 views.
Guardsman26

From: Guardsman26

24-Jun

NGSW concerns are:

- Chamber pressure of ~80,000 psi is breaking weapons and reducing barrel life to around 2,000 rounds - not sustainable / affordable long term

- Muzzle velocity of 3,000 fps for a 6.8 mm projectile with a mass of 7-9 grams creates a massive felt recoil issue - more than 7.62 mm NATO -so training burden is increased. Even if you are using an active reticle fire control optic, pre-emptive flinching among male and female soldiers (a common problem in my day when teaching recruits to shoot) will reduce hit probability. 

- Ammunition weight is basically the same as 7.62 mm not less. This increases the infantry soldier's burden when every bit of feedback coming out of Iraq and Afghan tells us we need to reduce it. 

Basically, we are equipping infantry with a calibre that's equivalent to .300 Win Mag. 

The need for overmatch is understood, but are the trade-offs worth it? Would it not be better to leave the task of long range shooting against enemies wearing body armour to snipers / designated marksmen equipped with .338 rifles? Or to reduce the Level IV defeat requirement to 300 metres? 

Assuming, the uS Army were willing to accept a reduction in range for NGSW, would a 6 mm EPR-style bullet be sufficient to pierce body armour and incapacitate a target behind it?  (i.e. Is 6 mm at 3,000 fps sufficiently lethal?) I would be interested in Emeric's thoughts on this. 

 

njb3737

From: njb3737

24-Jun

I share your concerns however do we actually know the details ( the numbers ) for areas such as barrel life and felt recoil ?

looking at the available on line material  for the SIG 6.8mm Spear rifle I think you are correct in terms of the felt recoil however I feel the Textron CT rifle has promise in this area ( and weight v's 7.62).

Again viewing the video footage from the Textron / tactical Rifleman promotional vid - felt recoil and ammo weight are at worst comparable to 7.62mm NATO.

I think we need a lot more real evidence before writing this off & I suspect the Textron offering has the edge in the areas of our concern.

SIG is clearly marketing the life out of their bid - pushing on line video content and articles with I suspect one eye on future MG and civil sales if they fail.

SIG are 'clever' in not publishing any comment by firers in the promotional vids on the felt recoil of the rifle which makes me suspicious. 

By contrast Textron have ( albeit only in one vid ) allowed comment.

My take on it is this:

Textron will win.

SIG knows it and is playing a game to promote their MG's with a mind to future MMG .338 and possibly SOCOM 6.8 contracts.

GD - dead in the water.        

poliorcetes

From: poliorcetes

24-Jun

Why pressure chamber would reduce barrel life? Barrel life depends of Vo, right? Why a Vo slightly slower than M193 would reduce so much barrel life?

And how Textron CT cartridge is going to weight the same than conventional 7.62?

stancrist

From: stancrist

24-Jun

Guardsman26 said:

NGSW concerns are:

- Chamber pressure of ~80,000 psi is breaking weapons and reducing barrel life to around 2,000 rounds - not sustainable / affordable long term

Is chamber pressure of the True Velocity ammo ~80,000 psi?  They give the impression that 6.8 TVCM has chamber pressure comparable to 7.62 NATO, thereby enabling easy conversion of legacy weapons.

https://www.youtube.com/watch?v=bL1wF-nCGc4

"True Velocity’s ammunition – and particularly our 6.8 TVCM cartridge – are changing the paradigm,” Tedford said. “It turns out you don’t have to operate at unsafe chamber pressures in order to generate increased velocity, enhanced terminal performance and improved accuracy. Our cartridge achieves all of these things, while maintaining safe operating pressures and drastically reducing the overall cartridge weight."

Delivers Next Gen — True Velocity (tvammo.com)

===============================

Guardsman26 said:

- Ammunition weight is basically the same as 7.62 mm not less. This increases the infantry soldier's burden when every bit of feedback coming out of Iraq and Afghan tells us we need to reduce it.

SIG cartridge weight is basically the same as 7.62 NATO, but Textron and True Velocity cartridges weigh considerably less than 7.62 NATO.

But, all three 6.8 rounds are just as bulky as 7.62 NATO, which results in 20-rd mags.  A 220-rd basic load would require a lot of pouches...

===============================

Guardsman26 said:

The need for overmatch is understood, but are the trade-offs worth it? Would it not be better to leave the task of long range shooting against enemies wearing body armour to snipers / designated marksmen equipped with .338 rifles? Or to reduce the Level IV defeat requirement to 300 metres? 

Those ideas -- as well as other alternatives suggested previously in this thread -- might work.  The question is, will the US Army be open to other options?

===============================

Guardsman26 said:

Assuming, the uS Army were willing to accept a reduction in range for NGSW, would a 6 mm EPR-style bullet be sufficient to pierce body armour and incapacitate a target behind it?  (i.e. Is 6 mm at 3,000 fps sufficiently lethal?) I would be interested in Emeric's thoughts on this.

I cannot answer that question.  I have zero data on 6mm EPR penetration performance.

autogun

From: autogun

24-Jun

stancrist said:

True Velocity’s ammunition – and particularly our 6.8 TVCM cartridge – are changing the paradigm,” Tedford said. “It turns out you don’t have to operate at unsafe chamber pressures in order to generate increased velocity, enhanced terminal performance and improved accuracy. Our cartridge achieves all of these things, while maintaining safe operating pressures and drastically reducing the overall cartridge weight."

Sure it does - but the advantage comes from a longer barrel, there's nothing miraculous about the performance of their ammo. 

JPeelen

From: JPeelen

24-Jun

Higher chamber pressures from a compact cartridge can only be achieved via hotter gas temperature. At the same time there is much more gas produced than by the comparably tiny propellant charge of the M193 cartridge. 

As a result, the throat is exposed to more gas at significantly higher temperatures flowing through it.

poliorcetes

From: poliorcetes

24-Jun

But how such hotter gas would decrease barrel life even more than a, say, bullet travelling down the bore at 1150 m/s?

EmericD

From: EmericD

25-Jun

poliorcetes said:

But how such hotter gas would decrease barrel life even more than a, say, bullet travelling down the bore at 1150 m/s?

It is an accepted fact that barrel throat erosion is directly linked to flame temperature, hence an indirect effect of chamber pressure.

If you want to include bullet MV in the global picture, you need also to take into account that the M193 achieved 990 m/s in a 20" barrel, with a bullet with a SD of 0.156. The SD of the 6.8 mm bullet is 0.251, so that's equivalent of a 88 gr 5.56 mm bullet.

Now, just imagine that someone ask you to design a 5.56 mm cartridge able to launch a 88 gr bullet with a MV of 915 m/s from a 13" barrel. Do you think that this round will have something in common with the .223 Remington, or will it be closer to the .220 Swift, or even more "overbore"? 

EmericD

From: EmericD

25-Jun

We have already discussed this issue, but I think that:

- from a training & logistic point, we need the same platform for the role of the PDW and the role of the IW,

- from an ergonomic point of view, a future common cartridge should be build around the "micro action" of the 5.56 mm / 5.45 mm / 7.62x39 mm,

- the same constraint imply that you will probably have a 25 rounds magazine with a .30 Remington or 7.62x39 mm casehead, and 20 rounds with a 12 mm casehead,

- from a cartridge design point, a 6.5 mm VLD bullet will eat a lot of volume, so we need probably to aim at .224", .236" or .243" bullet diameter.

Having said that, I think that the current 6 mm ARC with a 95 gr lead-free bullet is probably all you need for covering most your combat need, add a .338 Norma sniper rifle and MMG at a higher organizational level to cover all the direct-fire missions.

Guardsman26

From: Guardsman26

25-Jun

I agree. 

A 6 mm EPR-style low-drag projectile in a cartridge based on a .30 Remington / 7.62 x 39 mm casehead (11.1 mm) seems the best compromise. However, a 12 mm casehead may allow sufficient extra energy needed to achieve some measure of range body armour defeat. 

I'm trying to remember what you said about bullet weights to achieve a suppressive effect. Is 95 grains enough?

Could a future pistol / PDW standard emerging around FN's 5.7 mm cartridge? This seems to have gained market acceptance above H&K's 4.6 mm offering. A PDW / SMG weapon could equip AFV and helicopter crews, vehicle drivers, and artillery personnel. It wouldn't need to be effective beyond 200-300 metres. 

Ultimately, 5.7 mm 6 mm and 8.6 mm would be a good mix of calibres.  

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