gatnerd

Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 282048 views.
gatnerd

From: gatnerd

27-Oct

A close up shot of TV's 6.8 NGSW 'Neckless' cartridge. I was really surprised by this - I figured there'd be a lot more internal neck/plastic supporting the bullet inside. But they have just a little, so really maximizing case capacity. 

This also gives us an idea of how Emeric's 5.56 Neckless might look in polymer using that Balle D projectile he developed. 

gatnerd

From: gatnerd

27-Oct

stancrist said:

So, does anyone have the September issue?  I'm wondering if it shows the weight of the SIG rifle?

I dont have the issue but its available from the same source I got this months digital G&A. Hopefully someone will snag it, as its apparently a '14 minute read' aka pretty indepth article on SIGs NGSW.

https://www.zinio.com/guns-ammo/console-32735-219406-i501475

Previously Soldier Systems had reported the weights for both:

https://soldiersystems.net/2019/05/23/sofic-19-sig-sauer-exhibits-next-gen-squad-weapons/

Gr1ff1th

From: Gr1ff1th

27-Oct

Yeah, It's already hitting 135gr @ 3000 FPS with 65KPSI, Imagine what it could do with the full 80KPSI out of a 22" Barrel, for applications like this the extra barrel length from a bullpup can be a huge boon, not so much with 5.56 IMO

Gr1ff1th

From: Gr1ff1th

28-Oct


For comparison the 6.5CT Carbine is 8.3 lb (According to Textron), however we have no concrete numbers yet on the Textron NGSW-R 

Msg 7519.1755 deleted
gatnerd

From: gatnerd

28-Oct

Ran the numbers; RM277 is still very heavy at 10.4lbs. 

TV RM277 weight analysis:

Troy 45 degree sights: 3.35oz

Manta Rail covers = 7g a piece; ~9 per rifle ( 9x7g=63g) 2.22oz

Lancer 20rd 7.62 mag = 6.4oz

Aimpoint CCO = 13.3oz

Brevis 7.62 Titanium suppressor = 10oz

Total = 35.27oz / 2.2 lbs

RM277 Tested = 12.6lbs

-Gear

RM277= 10.4lbs

K&M 17 .308 Bullpup = 8.2lbs 16”; 8.5lbs 20”

DT MDRX .308 = 8.7lbs 16”

Tavor 7 .308 = 9lbs 16.5”

RM277 6.8 = 10.4lbs 18.5”

That is just weirdly heavy. I imagine part of that is still being a prototype, plus having the extra complexity of the open bolt / close bolt firing ability. But still. Heavy. 

The slight wildcard in the analysis is the suppressor. I assumed the Titanium Brevis was used. However if it was Iconel one, which is 6oz, that would put the RM277 at 10lbs flat. Which is still heavy but would be less.

  • Edited 28 October 2021 2:12  by  gatnerd
gatnerd

From: gatnerd

28-Oct

Some notes from the article now that I've re-read it:

RM277 Rifle

-Tested model 18.5” barrel; ‘production model’ 20”

-32.25” long w/ suppressor w/ 18.5”

-Rifle ~1moa in testing; a few flyers outside of MOA due to meh trigger

-Tworx I-rail can share power and data to optics and accessories

-Can be fired in open and closed bolt configuration

Ammo

-Claim 6.8 TVC max velocity is classified (ie higher then 135gr @ 3000fps)

-G&A Tested ‘comercial load’

-Can use less powder bc less energy loss due to not heating chamber like brass

-TV tested 60 different St. Marks powders for optimal performance

-Makes clear that military version will NOT be 80kpsi so as to allow backwards compatibility with existing weapons

-6.8 TVC Commercial load @ 65kpsi is ‘lower pressure and velocity,’ ‘different internal case geometry’ then Gov’t load;

-6.8 TVC Commercial = 135gr @ 3000fps from test barrel of unknown length

-6.8 TVC Commercial load did 5 shot 0.23” group from Accuracy International AX rifle

.....

The ammo difference between Civilian and Military is a bit weird. They make it clear that the .Gov NGSW round isn't 80kpsi, as that would prevent backwards compatibility. Yet they mention twice that the .Gov round is hotter then the 65kpsi commercial version, and also uses a different powder and internal case dimension. 

.....

So best guess is the TV .Gov load is somewhere between 66kpsi and 79kpsi, with the velocity of the GP EPR projectile over 3000fps. 

  • Edited 28 October 2021 6:53  by  gatnerd
EmericD

From: EmericD

28-Oct

gatnerd said:

A close up shot of TV's 6.8 NGSW 'Neckless' cartridge. I was really surprised by this - I figured there'd be a lot more internal neck/plastic supporting the bullet inside. But they have just a little, so really maximizing case capacity. 

I've just had some information "straight" from GD, and it's true that they experienced accuracy problems in some cases.

Due to the case geometry, they had to use a cold hammered barrel with a cut chamber (instead of a barrel with the chamber made during the hammering process). With this kind of process, the chamber is not always concentric with the bore, but with conventional ammo that's generally not a huge problem.

Unfortunately, with a plastic case (which is less rigid than a brass case) and a very short internal neck (as seen on the G&A picture) feeding from an automatic weapon, the problem is more acute.

Then add in the equation a bullet with a CoG not located in the best place, a weapon with a thin barrel and a suppressor, a recoil mitigation system that is inducing a lot of barrel vibrations, and this explains why GD experienced (in some cases) bullet in-bore balloting and large bullet yaw at launch, and also why G&A could achieve very good accuracy from a test barrel, or from a converted bolt action rifle.

My understanding is that the "out of alignment" chamber is much more acute with the Textron CT moving chamber design.

Gr1ff1th

From: Gr1ff1th

28-Oct

Thanks for your input Emeric, Do you think that it's possible that the Textron NGSW-R and AR could be having the (weakly) rumored accuracy issues or is it not likely to be true, because surely these issues would have been caught in LSAT/CTSAS and the preliminary phases of NGSW before it got to this point

Gr1ff1th

From: Gr1ff1th

28-Oct

Also would you say these edge case accuracy issued with the GD Rifle + TV Neckless are a Quality Control problem or are they fundamental to the design?, because it sounds like a possible QC issue to me

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