gatnerd said:

Yet the comparison is [also] fair if we view the systems by their 'fighting weights' as the two systems are actually deployed by the US Army.

I would be inclined to agree, but that idea ignores some pertinent facts.

1.  The US Army would not be the sole user.  The XM7 would also be used by the Marines, who have used suppressor-equipped M4 carbines for several years.  https://youtu.be/8-FuLw_6KgQ?t=98

2.  Since we're talking about the future, nobody knows how the M4 will be "actually deployed" if the XM7 is fielded.  The XM157 FCS is not dedicated to NGSW guns; it could also be used on the M4.

3.  Since we're talking about the future, nobody knows for certain if the XM7 will be "actually deployed" only with the suppressor attached.  Evidence suggests that it may not.

Are we totally sure that M7 is going to be fielded in numbers as an "assault" rifle? 

I find it really difficult to understand

I think they're gonna go through with it, and if they do well... 

It will tell us some stuff 

poliorcetes said:

Are we totally sure that M7 is going to be fielded in numbers as an "assault" rifle?

I am not totally sure that NGSW will be fielded at all.    But, the stated plan is to field the M7 as a replacement for the M4 in the infantry and some other close combat elements.

Interesting video.

He mentions ~5:30 zone that SIG uses 'Maraging steel' for superior barrel life. Curious what alloy that is and what properties.

https://en.wikipedia.org/wiki/Maraging_steel

Some discussion of it:

https://www.practicalmachinist.com/forum/threads/maraging-steel-for-us-civilians.195118/

Googling Maraging steels, came across this, from the makers of the H&K416's awesome barrels:

https://www.aubertduval.com/wp-media/uploads/2022/01/BD_fiche-petits-calibres_012022.pdf

No idea if this is the alloy, but description seems relevant:

And then this super fancy Italian shotgun also claims to use miraging steel, likely just for the bragging rights.

https://www.bosis.com/shotgun-basis-models/challenger/challenger-technical-detail.html

gatnerd said:

Curious what alloy that is and what properties.

These are very low carbon highly alloyed steels with high strength and ductility after heat treatment.
Maraging means "martensitic" and "aging".
A typical maraging steel is: X 3 NiCoMoTi 18-9-5
Allmost no carbon but lots of Nickel, Molybdenium and Titan

These alloyes are nothing new really. But they are pretty expensive and the required heat treatment could not be done by anyone in the past. This has changed in the last decades so the availability and price got better. Which means its now more commonly used. Its still not common but its also not obscure anymore.

Maraging steel has been around a long time.  I recall that it was used on the NASA Lunar Lander in the 1960's and has long been used for the tail hooks of carrier aircraft.  

I cannot resist to add that 32 CrMoV 12 10, the steel of HK416 "awesome barrels", had been the steel for G3 barrels for decades and one can order commercial barrels using it from Lothar Walther, for example.     

JPeelen said:

I cannot resist to add that 32 CrMoV 12 10, the steel of HK416 "awesome barrels", had been the steel for G3 barrels for decades and one can order commercial barrels using it from Lothar Walther

Ah, very cool.

It seems super fancy to us in the US, because virtually all gun barrels here are pretty boring 4150cmv barrel steel. 'Premium' is having the barrel Cold Hammer Forged (standard practice in europe forever), as opposed to button rifled. (also part of why the majority of my collection is made in Europe)

The standard M4 of the US army is just button rifled 4150cmv, chrome lined, and reportedly starts to see accuracy degradation at 6-7k rounds. A good 4150 CHF barrel is hoped to go to 20k rounds. 

Meanwhile this 416 is still holding 4moa after 67,000 rounds:

https://soldiersystems.net/2013/03/30/canipe-correspondence-retiring-my-416/

I recall Emeric also reporting great results with France's 416 barrel testing.

....

Kind of random, do you happen to know what barrel steel Steyr uses for the AUG? 

In the US they had been using FN made CHF barrels, but reportedly they are now using Austrian blanks that are just finished in the US (a peculiarity of our import laws here.) If they're using the same / similar barrel steel to the 416/G3, I may have to snag an extra barrel.