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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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Neckless ammo   Ammunition <20mm

Started 20/8/21 by EmericD; 41490 views.
In reply toRe: msg 70
EmericD

From: EmericD

18/1/22

The first 5.56 mm NL ammo (brass case cut to 40.5 mm) were fired out of an EPVAT tube and a HK416 F just before Christmas.

Radar measurements confirm that the C7 of the bullet is 0.208 around Mach 2, and the bullet was perfectly stabilized.

As expected, the dispersion from the EPVAT tube was catastrophic (we fired the NL case out of a regular chamber), close to 10 MoA, along with the launch angle (above 10° in one case). The MV was ~905 m/s with a chamber max mean pressure of 305 MPa, versus 930 m/s and 320 MPa for the IMI 5.56 mm used as reference.

What wasn't expected was that the HK416 F-S ran perfectly with this low-pressure ammo, with decent (~3.5 MoA) accuracy (launch angle around 4° max), the same POI as M855 ball, a MV of 815 m/s and SD below 5 m/s...

The difference seems to be linked to the EPVAT chamber profile, we are going to slightly change the bullet profile to achieve a better bullet support during launch, and ~2 MoA dispersion should be possible from the EPVAT tube and the HK416 F.

We are also going to ramp up the pressure, probably up to 340-360 MPa, to get a MV around 850 m/s from a 14.5'' barrel. Or going "full throttle" and 400 MPa to reach 900 m/s from the same barrel length and more than 900 m of supersonic range from a carbine...

smg762

From: smg762

18/1/22

Do you have much knowledge of the 70s high velocity French experimental rounds....7.5 necked to 4.6.....Any idea of their speeds?

mpopenker

From: mpopenker

19/1/22

Emeric, thanks for info

But can you please remind us what is the end goal of the neckless brass case / round? Weight decrease? Or attempts to squeeze a longer and heavier ballistically optimized projectile into the old 5.56mm form-factor?

Gr1ff1th

From: Gr1ff1th

19/1/22

I'm not Emeric, but he's indicated it's the latter

EmericD

From: EmericD

19/1/22

Hi Max,

The objective was to check that we could use a "much better bullet" in a unmodified 5.56 mm weapon, and that we could launch this bullet at a sufficiently high MV.

It's just a preliminary step before seating this same bullet in a composite case, the ultimate goal is to be able to launch a lead-free bullet with a C7 CB above 0.20, at a MV around or above 850 m/s from a 14.5" barrel (so slightly better ballistics than a Mk262), with a cartridge weight below 9 g.

mpopenker

From: mpopenker

19/1/22

Thanks

Now that's what can be called a reasonable evolutionary approach.

gatnerd

From: gatnerd

19/1/22

EmericD said:

It's just a preliminary step before seating this same bullet in a composite case, the ultimate goal is to be able to launch a lead-free bullet with a C7 CB above 0.20, at a MV around or above 850 m/s from a 14.5" barrel (so slightly better ballistics than a Mk262), with a cartridge weight below 9 g

That'll be wonderful if it comes to fruition, and I sure hope it does.

Thanks for giving us the project update. 

Gr1ff1th

From: Gr1ff1th

19/1/22

Composite as in hybrid plastic and steel?, is that possible for your lab to do, or will you have to partner with TV?

gatnerd

From: gatnerd

20/1/22

It seems the Neckless concept is gaining ground. TV has now debuted a .338 Neckless:

https://www.thefirearmblog.com/blog/2022/01/20/shot-2022-6-8-tvc-cartridge-and-guns-to-be-available-commercially/

.338 TV

.338 seems to be the perfect format for this, in that weapons have not yet been fielded, so theres time to have chambers re-cut for neckless as opposed to .338 brass conventional.

stancrist

From: stancrist

21/1/22

gatnerd said:

.338 seems to be the perfect format for this, in that weapons have not yet been fielded...

Trouble is, whether neckless or necked, a .338 machine gun seems to be a solution in search of a problem... 

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