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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, particularly in larger calibres (12.7+mm).

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6mm ARC - new AR GPC cartridge   Ammunition <20mm

Started 4-Jun by gatnerd; 15117 views.
gatnerd

From: gatnerd

4-Jun

Hornady has released a new cartridge, reportedly a 6mm Grendel type cartridge optimized for 103-108gr 6mm VLD's:

https://www.hornady.com/6mmARC#!/

https://soldiersystems.net/2020/06/03/lantac-la-sf15tm-6mm-arc-chambered-rifle-dedicated-e-bcg/

Lantac’s new LA-SF15 6ARC 18’’ Rifle+1 gas system (pictured) delivers 2629 FPS at muzzle with 2457FPS at 100M (109.36 Yards) and 1408 FPS at 800M (874.89 Yards). Energy is 1657 Ft-lb (2246 Joules) at 100M (109.36 Yards) and 475 Ft-lb (644 Joules) at 800M (874.89 Yards) approx. Lantac has also developed a more compact 14.5’’ Intermediate gassed system that delivers 2483 FPS at muzzle with 2315 FPS at 100M (109.36 Yards) and 1302 FPS at 800M (874.89 Yards). Energy is 1285 Ft-lb (1742 Joules) at 100M (109.36 Yards) and 407 Ft-lb (551 Joules) at 800M (874.89 Yards) approx.

 

18" Data:

 

And 14.5" Performance:

 

Overall not a perfect cartridge by any means, but it looks to be the best commercially available 'GPC' compatible with the 5.56 2.26" COL. A purpose built rifle, with strengthened bolt to allow a "6mm NATO" full 62kpsi pressure ala 5.56/7.62, would likely boost performance into the 'pretty dandy' range. 

Very curious what the velocity would be with the 88gr Warner Flatline. 

  • Edited 04 June 2020 3:43  by  gatnerd
In reply toRe: msg 1
gatnerd

From: gatnerd

4-Jun

Apparently there has also been a small DOD order for 6mm ARC:

https://news.barrett.net/2020/06/03/barrett-announces-shipment-of-6mm-arc-rifles-to-us-dod/

Barrett Firearms Manufacturing, Inc. is pleased to announce that it has partnered with Hornady Manufacturing to chamber the REC7 rifle series in the new 6mm ARC offering.  The first production run of these rifles has already been delivered on time to the United States Department of Defense, fulfilling a contract that was awarded to Barrett late last year .

The combination of the proven REC7 DI gas system and the potent 6mm ARC cartridge creates a product that is consistently accurate and easy to shoot.  Carrying 24 rounds in the magazine, the 108 gr . ELD Match bullets leave the 18” Proof Research match grade stainless steel or carbon fiber barrel at over 2630 fps.  This easily gives the rifle supersonic capabilities past 1000 yards

QuintusO

From: QuintusO

4-Jun

Basically a factory version of 6mm AR. Great round.

EmericD

From: EmericD

4-Jun

QuintusO said...

Basically a factory version of 6mm AR. Great round.

So, it's based on a x39 mm case, not a shortened 6.8 mm SPC case?

The muzzle velocity quoted from a 18" (801 m/s) is interesting, because that's 20 m/s better than the .224 Valkyrie with a 90 gr bullet from the same barrel length, and the BC of the 108 gr ELD-Match seems between the 90 gr SMK and the 90 gr Berger.

So, now we have two very interesting rounds for the AR platform, the .224 Valkyrie that is working very well with 70-80 gr bullets, and this 6 mm that seems to work well with bullets in the 95-105 gr range.

QuintusO

From: QuintusO

4-Jun

Yes it's based on the venerable x39 case, the print released a while back has an error.

I've ordered some ammo for my reference collection, so I can give you more details then.

EmericD

From: EmericD

4-Jun

QuintusO said...

Yes it's based on the venerable x39 case, the print released a while back has an error.

 

I've ordered some ammo for my reference collection, so I can give you more details then.

So, it's more-or-less the "ideal" cartridge as discussed ~4-5 years ago with the Canadian DoD.

QuintusO

From: QuintusO

4-Jun

It beats the 6.5 Grendel, certainly. The big downside is there's no practical way to use lightweight magazines (aluminum, polymer) in a standard AR receiver set. You're forced to use steel mags, or go to a larger receiver pattern.

nincomp

From: nincomp

4-Jun

gatnerd said...

A purpose built rifle, with strengthened bolt to allow a "6mm NATO" full 62kpsi pressure ala 5.56/7.62, would likely boost performance into the 'pretty dandy' range. 

The Grendel case does not deal well with higher pressures in an AR platform.  The lower section of the case would need to be strengthened to avoid expansion in the area that is unsupported by the chamber.   I have seen the case expansion called the "Dreaded Grendel Belted Magnum" effect.  The stronger case would be heavier and have a slightly reduced volume.  Below are a couple of examples of this.

[Linked Image]

 Below shows the cross section of a 6.5 Grendel case (next to a 6.8 SPC case, which is known to handle higher pressures).

[Linked Image]

EmericD

From: EmericD

4-Jun

QuintusO said...

It beats the 6.5 Grendel, certainly. The big downside is there's no practical way to use lightweight magazines (aluminum, polymer) in a standard AR receiver set. You're forced to use steel mags, or go to a larger receiver pattern.

ARX-160 maybe ?

QuintusO

From: QuintusO

4-Jun

That rifle is a steaming pile of trash, please no.

  • Edited 04 June 2020 13:27  by  QuintusO
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