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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True Velocity polymer case ammo   Ammunition <20mm

Started 17/11/17 by gatnerd; 12004 views.
In reply toRe: msg 17
gatnerd

From: gatnerd

12/7/19

True Velocity is still plugging away.

Guns and Ammo has two good segments on them. The first covers a visit to the TV factory, and how tight the tolerances are on the cases (holding to 0.001" on the case wall; 0.0005" on the case mouth.) We also see confirmation that bullets are glued into the case mouth, which appears to be essential for these polymer cases vs brass/steel.

https://www.gunsandammo.com/show/guns-and-ammo-tv/videos/181995/325947

And an G&A article:

https://www.gunsandammo.com/editorial/true-velocitys-new-polymer-cased-ammunition/247607

The more interesting video is the on on TV's Facebook, showing a different clip. This shows, for the first time I'm aware of, polymer 5.56 cases being fired. The shooter also describes a dramatic decrease in chamber heat due to the polymer cases (firing 100rd's FA and then being able to put a finger in the chamber right after without burning.)

https://www.facebook.com/truevelocityammo/videos/469202490508619/

Freshly ejected cases are cool enough to be stuck in the shooters mouth:

Farmplinker

From: Farmplinker

13/7/19

The important question: will it be cheaper than Wolf?

In reply toRe: msg 19
gatnerd

From: gatnerd

25/1/20

True Velocity is going to be partnering with Sierra and releasing their cases for commercial sale:

https://www.wideopenspaces.com/sierra-bullets-true-velocity-unveil-competition-grade-composite-cased-ammunition/?fbclid=IwAR1aKh5LzNe_0Xe_P2F6vFrWxoIRmfZydIj6KMrescmgn2mVORQzMVdO6l0

This year at SHOT Show 2020, Sierra Bullets and True Velocity introduced the first-ever competition-grade line of composite-cased ammunition.

In fact, these cartridges are putting up numbers unsurpassed by brass-cased match-grade cartridges, as they're capable of sub-MOA accuracy at extended ranges and single-digit standard deviation in muzzle velocity.

 

The composite neck and body of the case also allow for excellent wall thickness uniformity, as well as precisely aligned features with minimal runout.

Thanks to the composite, engineers can control the internal geometry of the case, meaning they can tweak the powder chamber to get optimal internal ballistics.

With better burn efficiency, the ammo requires 10 percent less propellant, which results in less barrel wear over time and less recoil with each shot.

Boxes will hit the shelves sometime in 2020, and will initially come in .308 Winchester with Sierra's 168- and 175-grain MatchKing and Tipped MatchKing bullets, as well as 6.5 Creedmoor with a 142-grain MatchKing bullet.
QuintusO

From: QuintusO

25/1/20

I need their 5.56 ammo so I can pull the bullets and load M855A1 EPRs to put in my Kel-Tec RDB so I can fight robots while my built-in cybernetic mirrored shades are deployed.

In reply toRe: msg 22
autogun

From: autogun

16/9/20

Some more pictures of TV .308 Win here: https://forum.cartridgecollectors.org/t/308-win-from-sierra-true-velocity-composite-cartridge-case-new-for-2020/37308

A thought crossed my mind: as I understand it, one problem with polymer versions of metal cases is that the necks have to be very thin, hence TV preferring a neckless design for their clean-sheet 6.8 mm NGSW. A alternative approach might be to design a bullet with a reduced diameter at the case mouth, so the neck can be thicker. Not sure if this would allow enough contact with the bore to keep the bullet stable, though.

QuintusO

From: QuintusO

16/9/20

You certainly can do it that way, but there's really no reason to. The TV-NGSW neckless format has superior propellant capacity and compression characteristics.

nincomp

From: nincomp

16/9/20

As noted, a neckless design can allow a larger powder charge for a given length cartridge, or a longer projectile with the same charge.  There have probably been designs that tried to tuck the neck backwards into a metallic cartridge body to get the same effect, but I have never seen one. 

Years ago in one of the GPC threads here, I proposed the idea of using a neckless variation of the 7.62x51 to permit the use of a longer, higher-bc bullet.  My thinking was that this would permit a reduction of propellant and recoil while still giving acceptable long-range performance.  To be honest, I was pretty proud of myself for the idea.... for maybe 24 hours.  The next day, Badcow (Emeric) posted that there was already a patent pending on the idea, but he couldn't discuss details.  Sigh.

I am curious to see how much of the bullet's tail protrudes into the propellant space of the neckless designs.  I have often read that doing so with a normal cartridge can reduce accuracy.  Maybe this reduction is too small to be an issue for a military cartridge?

eta: clarity

  • Edited 16 September 2020 14:08  by  nincomp
autogun

From: autogun

16/9/20

QuintusO said:

You certainly can do it that way, but there's really no reason to. The TV-NGSW neckless format has superior propellant capacity and compression characteristics.

For new design weapons and ammo, no argument. I was thinking in terms of ammo fired from existing guns with no chamber modifications. As I recollect, a neckless version of the 7.62 x 51 might suffer from some disadvantages, to do with the bullet needing to jump into the leade?

autogun

From: autogun

16/9/20

nincomp said:

I am curious to see how much of the bullet's tail protrudes into the propellant space of the neckless designs.  I have often read that doing so with a normal cartridge can reduce accuracy.  Maybe this reduction is too small to be an issue for a military cartridge?

There is an accuracy advantage in having no ullage (i.e. the propellant exactly fills the available space). This is because propellant burn is more consistent. I recall seeing a presentation about the .50 BMG which was found to differ in chamber pressure, MV and accuracy depending on whether the ullage was at the primer or bullet end. One of the less well-publicised advantages of polymer cases is that their wall thickness can be adjusted for each loading to ensure that there is no ullage.

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