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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; 555294 views.
ZailC

From: ZailC

27/11/19

I read your original post too critically, sorry. However I doubt that the surrogate will be entirely satisfactory in flight. Behavior at transition to subsonic will likely be a problem. Gyroscopic properties of spin-stabilized, high-length-to-diameter projectiles are notoriously touchy. 

gatnerd

From: gatnerd

27/11/19

"However I doubt that the surrogate will be entirely satisfactory in flight. Behavior at transition to subsonic will likely be a problem. Gyroscopic properties of spin-stabilized, high-length-to-diameter projectiles are notoriously touchy."

Yes, I imagine once the AP Tungsten 'Special Purpose' projectile is developed, they will need to perform all manner of testing with the real SP projectile. I know from 5.56, different manufacturers of SS109/M855 have different levels of accuracy at 100yd, despite on paper being the same bullet (Winchester being notoriously inaccurate, IMI being considered quite good.) And thats with the same standardized projectile design. Differences between lead core and tungsten core projectiles is likely to be quite different. 

I think the Surrogate just needs to approximate the form factor and weight of the AP load for the purpose of cartridge and weapon design. Example - can the prototype weapon and cartridge fire a 1.3" / 0.75" ogive 140gr VLD @ 3000fps. All it needs to do is show that the weapon can feed that projectile shape reliably, and that the cartridge is sufficiently powerful to launch that weight of projectile to the desired velocity. 

For that, a lead core Surrogate of the same form factor and weight is likely a good enough approximation. 

EmericD

From: EmericD

28/11/19

ZailC said...

Gyroscopic properties of spin-stabilized, high-length-to-diameter projectiles are notoriously touchy. 

It's not a problem anymore with an EPR type bullet, or with "solid" type bullets.

Due to the bullet manufacture, it's possible to have a clean "edge" at the rear of the boat-tail that mostly avoids the large negative Magnus moment generally found with conventional jacketed bullets in transsonic flight.

gatnerd

From: gatnerd

18/12/19

SIG has announced the commercialization of their 6.8 NGSW Cartridge, which will be now known as '.277 FURY.'

http://soldiersystems.net/2019/12/18/sig-sauer-announces-new-bolt-gun-and-caliber-sig-cross-277-sig-fury/

In addition to the rifle, they are commercializing the 6.8mm ammunition developed for the US Army’s Next Generation Squad Weapon program as the 277 SIG FURY round. SIG claims to be getting 3000 FPS velocity from a 16″ barrel when fired from the CROSS. This owes to the cartridge’s three-piece design case which features a brass case and steel head held with a clip. This is the same cartridge design being offered to the military, but now coming to you.

While the 277 SIG FURY cartridge is awaiting approval from SAAMI, SIG expects it be certified for SHOT Show [Jan 2020].

 

Here is a 6.2lb bolt action rifle + suppressor being fired with the .277 Fury; despite the high power, recoil is quite manageable:

https://www.youtube.com/watch?v=FJLbbVh47aE&feature=emb_title

 

Overall this is a significant development for several reasons:

-Commercialization indicates SIG believes the cartridge and 3 piece case to be 'done' and ready for prime time / immediate fielding 

-By commercializing the cartridge and submitting to SAAMI, that means that whether the NGSW is canceled, or if another cartridge is chosen, SIG's NGSW performance will now be available to other manufacturers should they choose to develop weapons around it. 

-Commercialization of this .277 cartridge offers a high powered rival to 6.5 Creedmoor - possibly foreshadowing a decline in that cartridges hitherto meteoric rise in popularity. 

autogun

From: autogun

19/12/19

 

gatnerd said...

SIG has announced the commercialization of their 6.8 NGSW Cartridge, which will be now known as '.277 FURY.'

 

An interesting development. I suspect that the SIG approach will be more popular in the US commercial market than the GD-OTS (let alone the Textron) simply because the cases are easily reloadable. 

Also interesting that the calibre designation for both SIG and GD is .277 - not only not metric, but bullet rather than bore diameter which is unusual for military rifle cartridges (the .338 LM is the only other one in recent history I can think of, and that just carries over an existing commercial designation - as does the bore-diameter .300 WM). If adopted, the US Army will presumably apply its own designation - 6.8 mm M-something?

 

stancrist

From: stancrist

19/12/19

autogun said...

Also interesting that the calibre designation for both SIG and GD is .277 - not only not metric, but bullet rather than bore diameter which is unusual for military rifle cartridges...

But not at all unusual for commercial rifle cartridges, or commercial versions of military rifle cartridges.

Image result for .243 winchester

Related image

autogun

From: autogun

19/12/19

stancrist said...

autogun said...

Also interesting that the calibre designation for both SIG and GD is .277 - not only not metric, but bullet rather than bore diameter which is unusual for military rifle cartridges...

But not at all unusual for commercial rifle cartridges, or commercial versions of military rifle cartridges.

Of course - commercial practice is entirely inconsistent:

Bullet diameter mm/inches

Bore diameter mm/inches

Cartridge designations

5.60/.221

5.5/.217

5.45 mm Russian

5.69/.224

5.56/.219

5.56 mm, 5.6 mm, .218, 219, .22, .220, .221, .222, .223, .224, .225, .226

6.2/.244

6.0/.236

6 mm, .240, .243, .244

6.53/.257

6.35/.25

6.35 mm, .25, .250, .257

6.71/.264

6.5/.256

6.5 mm, .256, .260, .264

7.04/.277

6.86/.270

6.8 mm, .270, .277

7.21/.284

7.0/.276

7 mm, .275, .276, .280, .284

7.82/.308

7.62/.300

7.5 mm, 7.62 mm, 7.63 mm, 7.65 mm, .30, .300, .307, .308

7.90/.311

7.7/.303

7.62 mm (Russian), 7.65 mm (Belgian), 7.7 mm, 8mm Swedish, .303, .311

8.20/.323

7.92/.312

7.92 mm, 8 mm (most - but not all)

8.59/.338

8.38/.330

8.58 mm, .33, .330, .338, .340

12.9 / .510

12.7 / .50

.50, 12.7 mm

 
JPeelen

From: JPeelen

19/12/19

I did not see any bullet weight mentioned in the SIG announcement. Without it, the figure 3000 fps has not much substance to it.
stancrist

From: stancrist

19/12/19

autogun said...

stancrist said...

autogun said...

Also interesting that the calibre designation for both SIG and GD is .277 - not only not metric, but bullet rather than bore diameter which is unusual for military rifle cartridges...

But not at all unusual for commercial rifle cartridges, or commercial versions of military rifle cartridges.

Of course - commercial practice is entirely inconsistent...

Perhaps I was not clear.  The point I was trying to make is that .277 is a commercial caliber designation, not a military one.

If the SIG (or GD) round is adopted by the military, it will almost certainly get a metric (bore diameter) caliber designation.

  • Edited 19 December 2019 12:07  by  stancrist
gatnerd

From: gatnerd

19/12/19

The projectile and cartridge is based of the NGSW, so some sort of 120-140gr .277/6.8 VLD.

120gr 6.5 Creedmoor is ~2750 from a 16", so 3000fps for even a 120gr 6.8 from a 16" would be blisteringly fast.

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