nincomp said:

Emeric, have you had the opportunity to section a True Velocity case?  If so, was some type of reinforcing added to the shoulder and neck area.

Unfortunately, no, and the people from TV took large efforts to be sure that no empty cases remained on the ground (or into pockets) after firing.

nincomp said:

It would resemble the 6.8 TVC case with a hollow tube attached to the front. 

Instead of a tube that could produce feeding problems, make something like 3 or 4 petals following the bullet ogive, that could open to let the bullet pass.

nincomp said:

To be honest, if no pics show up soon, I am tempted to buy a some, just so I can section it.   For what it is worth, the 6.8 TVC ammo case is made in two pieces, with the neck welded onto the body.

Well, it looks like you can save your hardly-earned  money.  I just found a photo showing the two-piece construction.

EmericD said:

       stancrist said: If polymer cases need a greater thickness of material at the neck, how do you explain https://youtu.be/G1DCJsMKJb0?t=30 ?

The magic of the Internet. Now, take the 100,000 or about M240 in service in the US Army and try to duplicate the video, I'm pretty sure that the result will be much different.

Okay, if True Velocity is concealing a flaw in this product...

...perhaps there is also a significant flaw in this product?

stancrist said:

Okay, if True Velocity is concealing a flaw in this product...

I won't call that "a flaw".

The GAU-8 is using aluminium cases to save a lot of weight, even if everybody (including the designers) knows that in case of a burn thru, you are going to lose the gun.

Lead-free primers are less reliable than leaded primers, but people want to use them because you reduce lead emissions.

So, even if a composite case split a neck every one in a thousand rounds, there's a lot of scenarios where you could use them.

EmericD said:

I won't call that "a flaw".

The GAU-8 is using aluminium cases to save a lot of weight, even if everybody (including the designers) knows that in case of a burn thru, you are going to lose the gun.

How many GAU-8 guns have been lost to burn thru of the aluminum case?

EmericD said:

So, even if a composite case split a neck every one in a thousand rounds, there's a lot of scenarios where you could use them.

If the neck separates from a cartridge case every one in a thousand rounds, I think most soldiers would consider that a rather serious flaw.  I sure would.

And if the USAF lost a GAU-8 to case burn thru every 1000 rounds, it's a safe bet they'd consider it such a serious flaw they wouldn't use aluminum cases.

Thanks for finding those photos of the TV case.  I recall hearing a TV rep mentioning that they could optimize the powder column but was unsure if they had done so on their "normal" ammo.

EmericD said:

Instead of a tube that could produce feeding problems, make something like 3 or 4 petals following the bullet ogive, that could open to let the bullet pass.

It would be interesting if they could do something like that and allow the ogive to be recessed in that false "neck" section.   I had been thinking about that too.  It would allow existing cartridges like 5.56x45 or 7.62.51 to use bullets with longer ogives.  The trick would be to assure that the bullet stays supported and aligned with the bore and that the petals stay attached to the case.

You're welcome.  Glad I could help.

EmericD said:

Dimensions of the 6.8 mm GP according to the single picture available, probable error of 0.01" (1 pxl on the picture): BOAL: 1.41" Ogive: 0.825" Shank: 0.380" BT: 0.205" EDIT: those dimensions lead to a bullet mean density of 9.4 g/cm3, or a 120 gr bullet if the density is 8.4 g/cm3.

I have wondered if the NGSW trials actually used the bullet in the photo.  That is partly why I have been using the phrase "high-BC EPR-style bullet."  Do we know for certain that they used this particular bullet?