https://www.thefirearmblog.com/blog/2022/04/26/us-army-discusses-ngsw/

Most interesting line:

Interestingly, Brigadier General Boruff also noted that his team was not ‘allowed’ to work with any of the submitting vendors until after the downselect. He said “the exciting point for us is that we can now work with SIG Sauer, we can refine some of the pressures in the weapon which will enhance the ammunition as we move forward.” As the US Army builds up its ammunition manufacturing capability Brigadier General Boruff explained that weapons and ammunition refinement will continue.

Which means what, exactly?  

Thats the question. More pressure? Less? We'll have to see. 

"as we move forward"

im assuming this means the army will use the spear as a platform like the m4...? will they field it sooner or after years of fine tuning?

 

I honestly think that projects like NGSW should be done in at least two phases.  The goals in this case were beyond current feasibility, so the vendors had to guess which compromises would be preferred.  Although we don't yet know the initial "requirements" in the NGSW RFP, we have seen reports that those for the velocity and weight reduction were reduced after the fact.   It seems that the initial downselect eliminated who guessed wrong and decided to meet velocity "requirements".  They submitted  larger-diameter conventional cartridges at "normal" pressures (6.8 short mag and 6.8 Sherwood).   The eventual winner chose unusually high pressure cartridge requiring a relatively expensive case, the same size as 7.62x51 and with minimal weight savings. 

Competitions where none of the competitors can meet the aspirational goals lead to a situation of : "We would have proposed something different if we had only known the compromises you woulsd prefer." A second round of competition between TV and SIG would have allowed both companies to home in on functional improvements.  I would guess that TV would raise chamber pressure, permitting either a shorter version of what was submitted or non-bullpup versions.  They would probably submit a belt-fed LMG.   I have less of an idea of that SIG would change, but possibly felt-recoil reduction of its rifle.  

Being an engineer, I also think that contracts like this should cover development expenses so that best ideas from all the competitors can be combined.   In a competition like this, seldom does one competitor have ALL the best ideas.  We may never know if the best compromise was a high-pressure TV cartridge in SIG weapons, for example.  That is, unless TV works on a similar idea to sell to other countries.

nincomp said:

Competitions where none of the competitors can meet the aspirational goals lead to a situation of : "We would have proposed something different if we had only known the compromises you woulsd prefer." A second round of competition between TV and SIG would have allowed both companies to home in on functional improvements.  I would guess that TV would raise chamber pressure, permitting either a shorter version of what was submitted or non-bullpup versions.  They would probably submit a belt-fed LMG.

I don't see any logical reason for those conclusions.

1.  Being chosen for a second round would validate TV's submission of a bullpup NGSW-R and -AR, giving TV no cause to develop non-bullpup versions and/or a belt-fed LMG.

2.  Even if TV somehow concluded that they should switch horses mid-stream, who would design and develop a belt-fed LMG for them?  I doubt either TV or Beretta is able.

stancrist said...

2.  Even if TV somehow concluded that they should switch horses mid-stream, who would design and develop a belt-fed LMG for them?  I doubt either TV or Beretta is able.

Given that the TV round works out of anything that can run 7.62x51mm, FN or Knights Armament could have a go?

gatnerd said:

       EmericD said: at least 2 competitors (True Velocity and PCP tactical) used outsourced 135 - 136 gr solid copper bullets for their in-house development phase

We also have Soldier Systems initial reporting on the SIG's specs, which quoted 135gr @ 2850fps 13", 3000fps 16". So thats our 3rd indication of 135gr being relevant.

I agree that it is reasonable to conclude that the 135gr weight of the surrogate bullets is relevant.  However, that information does not necessarily indicate that the steel-tip GP projectile weighs ~135 grains.

Considering the expected cost of the tungsten-tip SP armor-piercing bullet, I think it's far more likely that all of those 135gr surrogate bullets duplicate the weight of the SP round, not that of the GP projectile.

The certainty in this forum that the pictured GP bullet weighs only circa 120 grains would seem to support that idea.

RovingPedant said:

Given that the TV round works out of anything that can run 7.62x51mm, FN or Knights Armament could have a go?

Perhaps they would be willing. 

If TV paid them enough $$$$$.

GD/TV may not have switched to conventional layout, but merely demonstrating acceptable velocity from a shorter barrel would make a conventional layout an option.  SIG demonstrated a conventional layout designed for higher pressure.  SIG also demonstrated a LMG.  If the contract had been written allow a mix and match of cartridges and weapons, TV ammo in SIG weapons would have been an option.  As I stated, seldom does one competitor have all the best ideas.  Often needless complexity is added just to circumvent someone else's better idea.  Look at the mess with new rifle selection in Germany for an example.

Depending upon the design, it is often not terribly difficult to modify an existing design to handle the higher pressure. To give you an idea, Olympic arms and Dtech both sold modified AR15's that shot the WSSM cartridges that had 0.535" diameter case heads and 65,000 psi chamber pressures.   Those cartridges produce slightly more backforce than the 6.8 SIG Hybrid at 80,000psi.  The change mainly involved increasing the diameter of the bolt and barrel extension.  From interviews with SIG reps, it appears that SIG kept the same bolt diameter as their model 716 7.62x51 AR)  and just changed to a stronger steel.

Although I am certainly not an expert of modern machine guns I know that many of them use use a rotating bolt that locks at the front of the receiver.  This means that receiver stretching is less of an issue than with lever or flapper locking designs that require a significant length of the receiver to withstand higher forces.

I would also be stunned if General Dynamics had not proposed a variant of their .338 LWMG, which was designed for comparable bolt forces.