True Velocity claims for new 6.8 cartridge...

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ed308

New member
More on the new 6.8 cartridge. True Velocity is claiming their new case designed is capable of withstanding in excess of 80,000 PSI chamber pressure...

“We’ve developed and are currently validating a revolutionary 6.8mm case design to support the (GD-OTS) submission for the NGSAR program that we feel cannot be achieved using cases built from brass or even a combination of steel and composite,” said True Velocity Chief Marketing and Sales Officer Pat Hogan. “We think it will change the paradigm of cartridge design and cause the ammunition industry to reconsider what is ballistically achievable in small arms ammunition.”

Hogan indicated that early testing has shown the new case design is capable of withstanding in excess of 80,000 PSI of chamber pressure, while generating muzzle velocities in excess of 3,100 feet per second."

https://www.gunsandammo.com/editorial/true-velocity-forms-strategic-alliances-with-dillon-aero-and-general-dynamics/331240
 
W

Wyosmith

New member
3100 FPS would not be too impressive for a 100 grain bullet. if it takes 80,000 PSI to get it. I have chronographed 2985 with 90 grain 6.8s from my own gun.

But if that was a 130 or 150 grain bullet---- that would be a REAL step up.

I am wondering if the Army is going to have top end 270 Winchester ballistics in an M4 size carbine that holds 30 rounds, and heats up less then the currant 5.56, with ammo that is lighter.

THAT would be impressive. (REAL impressive to Taliban, and other creatures who are on the other side)
 
9

9x19

New member
I wonder how 80,000 PSI chamber pressure translates to rearward thrust? Bolt lugs might need to be a bit heftier?
 
J

jmr40

New member
There are too many rumors floating around about this. I'm taking the "wait and see" approach. If they can make it work, and make it reliable then I'm all for it. But I'm concerned about the reliability and durability of a rifle and cartridge pushed that hard.

One of the lessons learned from early M-16's is that in the pursuit of more muzzle velocity they chose a powder that made early rifles and ammo unreliable.
 
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Bartholomew Roberts

Moderator
Insulating the chamber from heat should help with heat checking and contribute to a longer service life, assuming they take that heat with them when they eject. Cartridges melting to the chamber after 5 minutes might be an issue though.
 
T

T. O'Heir

New member
"...a revolutionary 6.8mm case design..." That's just experimenting with the use of polymers for the case material. As I recall, HK did it eons ago.
"...capable of withstanding in excess of 80,000 PSI of chamber pressure..." 80,000 PSI is kind of low. .30-06 Blue Pill ammo runs 70,000 plus, as I recall. JC himself loaded some issue brass to 120,000 PSI with no fuss to the case.
Anyway, any new ammo must work in existing weapons to be of any use.
 
S

stagpanther

New member
Yesterday I went out fired some of shell shock's "binary" (my words, not their's) cases in 9mm--some of the 90 gr bullets where leaving the muzzle at almost 2000 fps, which I estimated were generating something in the neighborhood of 42,000 psi. They've told me some people have been getting around 3000 fps with lightweight composite bullets. No pressure, flow, expansion or primer deformation signs whatsoever. They are rated to 65,000 psi. Their cases were around the same price as conventional brass and are actually lighter. Only catch is you have to use their sizing and expander dies. They are rolling out their follow-on pistol cartridge calibers imminently, and rifle bottlenecks to follow. This makes sense to me rather than the cost of a small used (and unreloadable) space shuttle booster with each shot.

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J

Jim Watson

New member
They can "rate" the case to anything they want to, it is not really holding chamber pressure. As 9x19 says, more pressure will require a stronger action.

Weight saving is a real advantage.

I remain to be convinced on their notions of heat transfer. A "composite" case can insulate the chamber but it is not going to carry as much out the ejection port. The energy has to go someplace. I think I want a Stellite throat.
 
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