For the sake of this whole program, and the future of small arms in general, I really, really hope that they've found a way to maintain sub 0.1mm tolerances during full auto fire, it's already got acceptable accuracy in the LSAT so by extension it should be fine in the NGSW-AR, It's the NGSW-R Carbine I'm worried about,  I (And everyone here probably) would also like to see a G&A Issue on their entry, seeing as they're the only one to not have one yet, but that's up to Textron obviously

So in terms of G&A's article on SIG's NGSW, not as illuminating as G&A's article on TV.

But there were a few interesting points.

-Army NGSW requirement is 6,000 round barrel life, but SIG is hitting 12,000 rounds barrel life despite their 80,000psi cartridge.

(This is the most exciting and interesting point; if barrel life has been solved then the future for high velocity 'overbore' cartridges looks very bright.) 

-SIG's ammo can run 80kpsi, but also has increased powder capacity due to the thinner brass walls of their case. 

-SIG's rifle is described as having 'stout felt recoil' but their LMG is described as being as controllable as the 5.56 M249. 

Close up of sectioned SIG 6.8:

EmericD said:

That was my initial understanding, but I was wrong. The "smoke screen" on this program is denser than anticipated!

That is intriguing.

Was any indication given to confirm the 135gr @ 3000fps general performance we've seen published? Or is there the chance that those specs in and of themselves are also a "smokescreen"?

Because if the EPR GP we've seen is around 125-135gr, and the actual AP load is using tungsten + a denser alloy then copper for the base, then the overall projectile weight would be a good deal heavier the 135gr. 

The point about barrel life exactly what I was thinking, why do so many people in this community (firearms) act as if current barrel technology is the be-all end-all, as if it would never improve, when in reality it HAS advanced, and now has matured to the point where you have people repeating the tired old "I bet these NGSW rifles will be barrel burners, they'll be useless after 2K Rounds!" being proven wrong, this is really exciting stuff and really opens to doors to huge improvements, Maybe Emeric should re examine his GPC paper, specifically his conclusions about bullets in the .243"-.236" range now that this is known

Edit : Although I think his issues with those calibres were his Relative Suppression Index, and his heat flux measurements, which probably could be revised now

Gr1ff1th said:

why do so many people in this community (firearms) act as if current barrel technology is the be-all end-all, as if it would never improve, when in reality it HAS advanced, and now has matured to the point where you have people repeating the tired old "I bet these NGSW rifles will be barrel burners, they'll be useless after 2K Rounds!" being proven wrong

Well really prior to this testing with NGSW, the firearms community hasn't been able to see a 'overbore' max performance round out of a military grade / next gen barrel. 

All these cartridges (xyz super fast) were in the past fired from button broach rifled match grade boltgun barrels, which while extremely accurate are not that durable, and did show noticeable degradations in accuracy within 1500-2k rounds. Absent proof that better results were possible, it was prudent to plan for the worst and look at more modest cartridges rather then betting on a moonshot. 

The real question for me is whether SIG is using a true 'next gen' flow formed super alloy barrel, or if they are just using a Cold Hammer Forged 4150 barrel with chrome lining, or perhaps a CHF Chrome lined barrel using H&K's 416 barrel steel. 

If they're getting 12k rounds from CHF Chrome lined steel, then really the world is wide open for the next generation of high velocity cartridges. 

gatnerd said:

Was any indication given to confirm the 135gr @ 3000fps general performance we've seen published? Or is there the chance that those specs in and of themselves are also a "smokescreen"?

It seems that the "135 gr @3000 fps" is what the TV ammo is achieving with a lathe turned copper bullet (as shown in G&A article) or with the 135 gr SMK bullet.

That doesn't mean that the XM1186 "GP / EPR" bullet is 135 g @3000 fps, nor than the XM1184 "SP / ADVAP" is 135 gr @3000 fps...

Gr1ff1th said:

Maybe Emeric should re examine his GPC paper, specifically his conclusions about bullets in the .243"-.236" range now that this is known Edit : Although I think his issues with those calibres were his Relative Suppression Index, and his heat flux measurements, which probably could be revised now

I did it in 2019 but didn't had the time to finish it / publish it yet.

The main driver for the review was that I previously focused on a 2.8" action length, but my current views are that a GP cartridge should be put into a GP rifle, and you can't make a GP rifle around a 2.8" action (unless you plan to enlist only soldiers above 175 cm).

Given the size distribution of soldiers, you "should" built your GP rifle around a 2.26" action (or nearest offer), and a slender .264" bullet will simply eat too much space, unless you are using a very fat CT case.

So my current views are that within the 2.26" action length, something ballistically similar to the 6 mm ARC, loaded with a ~95 gr bullet, is all that is needed. The Chinese 5.8 mm is also a very good contender for the GPC job.

1. Excuse me for the question, because probably it has been made more than once here but my memory fails just too much lately. Why do you think SiG decided for a steel + brass case instead of a pure steel one? I assume that there is a reason that compensates higher expenses and complexity but I cannot figure it out

2. If M1186 design ends into a "broad belt" factor (belt as the part of the bullet that is in full contact with the bore, I don't recall the name in English), even if chamber/barrel alignment is not as precise as it would be desirable... Could it compensate such disalignement and exit the muzzle properly oriented and with enough gyro stabilization?

Merçi in advance as always

EmericD said:

specs in and of themselves are also a "smokescreen"? It seems that the "135 gr @3000 fps" is what the TV ammo is achieving with a lathe turned copper bullet (as shown in G&A article) or with the 135 gr SMK bullet. That doesn't mean that the XM1186 "GP / EPR" bullet is 135 g @3000 fps, nor than the XM1184 "SP / ADVAP" is 135 gr @3000 fps...

That does open up some interesting possibilities in terms of what 'actual' performance is. 

TV has repped a 135gr projectile, SIG has repped a 135gr projectile, and Cobalt/Mars repped a 140gr projectile. All in the 3000-3200fps. 

But, that could have been based on launching the copper lathe turned 'surrogate' projectile, which as I recall was offered by the gov as a technical drawing for the companies to make for themselves. 

It could be the surrogate projectile is designed not so much to replicate weight, as volume and projectile shape...

At which point we could see the Steel EPR in the 125gr weight class, and the Tungsten AP could be quite a bit heavier ie 155gr + zone. 

Oy, now I feel like we know less then we did a week ago. 

gatnerd said:

It could be the surrogate projectile is designed not so much to replicate weight, as volume and projectile shape...

That doesn't make sense to me. 

For weapon development and function testing, I'd think surrogate ammo would need to have the same bullet weight (and muzzle velocity) as combat ammo.

Plus, the shape of the GP bullet is clearly not the same as that of the machined copper solid (which, IIRC, has only been reported in TV "commercial" loads).