gatnerd

Military Guns and Ammunition

Hosted by gatnerd

This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

  • 3358
    MEMBERS
  • 191143
    MESSAGES
  • 10
    POSTS TODAY

Discussions

Neckless ammo   Ammunition <20mm

Started 20/8/21 by EmericD; 42509 views.
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... 

gatnerd

From: gatnerd

21/1/22

Yes, but if it can serve as a fielded test bed for neckless ammo that’s at least a win for ballistic science, which is about the best we can hope for.

EmericD

From: EmericD

21/1/22

Right, even if a neckless .338 Lapua will do everything (and even more) a .338 Norma is supposed to do.

EmericD

From: EmericD

21/1/22

Gr1ff1th said:

Composite as in hybrid plastic and steel?

Yep.

Gr1ff1th said:

is that possible for your lab to do, or will you have to partner with TV?

We have contacts with EU industries that are willing to invest into this technology, but at first we are going to do this study "in house" because it's not really mature enough.

We need also to investigate cold-pressed bullet manufacturing that will include steel core, instead of all-brass machined bullets.

Farmplinker

From: Farmplinker

21/1/22

Er, 6.8 is .277, not .338. Waiting to see if one of the budget rifles gets chambered in 6.8.

stancrist

From: stancrist

21/1/22

Farmplinker said:

Er, 6.8 is .277, not .338.

You're right.

6.8 TV

.338 TV

In reply toRe: msg 87
Mr. T (MrT4)

From: Mr. T (MrT4)

22/1/22

Neckless just looks like it doesn't have a neck. I imagine its optimized design to material properties vs TVC cases in existing calibers.

It just has a fat neck to accommodate for properties plastic material and the shoulder is basically on the neck , the micro lip which seems to be on the picture is probably just the final seal , one of the questions is how well does the thick walled polymer 'neckless' neck seal the chamber upon firing?

In reply toRe: msg 72
EmericD

From: EmericD

25/5/22

A small update, but first, a warning.

The following operations were safe because before shooting the cartridges into real weapons, we fired them into an EPVAT barrel (Electronic Pressure, Velocity & Action Time) to check that the pressure and internal ballistics were in line with the AOP 4172.

Please, don't try to duplicate those tests if you don't have access to a proof barrel.

The process.

First, we selected a lot of IMI 5.56 mm M855 ball ammo, removed the bullets with a bullet puller (not the inertia hammer type) and saved the powder for later use.

Left to right, 4 SS-109 / M855 cartridges made by various manufacturers, one LC M855A1 and our shortened and reloaded 5.56 mm.

The 5.56 mm family, from left to right, one M193; 3 SS-109 / M855; one M855A1 and the second version of our test bullet.

The test bullet is a solid copper-alloy bullet, based on the design of the Mle1898D bullet, but with a slightly secant ogive (Rt/R = 0.75). On the second version we changed the boat-tail to a more conventional conical design instead of the original long & truncated ogive BT.

The ogive length is around 16.7 mm so we will need to trim the case length at a maximum length of 40.7 mm in order not to exceed 57.4 mm COAL.

The bullet length is around 26.9 mm, with a weight of 4.15 g (64 gr).

The primed cases were cut with a saw (don't do this at home).

The small saw used to shorten the brass.

The shortened case, the case mouth is rough and impractical at this stage.

After this rough cut, the primed case is trimmed to the proper length.

The trim length was supposed to be around 40.5 mm, but the crimping groove on the bullet second version was deeper and longer than expected, so we had to adapt and tried 40.2 mm and 40.65 mm case length.

After trimming the case to the proper length, we removed the external burrs on the case mouth. Since we used "never fired" cases, there was no "donuts" inside the case.

From left to right, case mouth after the first cut, after trimming, and after removing the burrs.

Powder saved during the initial bullet extraction phase was partially put back in the case, and the test bullet was seated.

During the first test, the bullets were crimped with a hydraulic tool which heavily deformed the case mouth, so we didn't crimp the bullet during the second test to check if some issues with bullet accuracy observed during the first test were not caused by improper bullet placement.

The final cartridges were then checked.

During our first test, we removed some powder from the original IMI load to stay well below 100% of loading density (the effect of the solid bullet was unknown), then the EPVAT tests revealed that the MAP was only ~300 MPa with the improved bullet (equaling to a MV of 900 m/s from a 20" barrel and 815 m/s in a 14.5").

During the second round of tests we increased the loading density step by step to reach a MAP of ~340 MPa and then ~360 MPa.

At this later pressure, the measured MV was above 930 m/s in a "pseudo Mk12" AR-15 with a 18'' barrel, duplicating the MV of the M855 bullet when fired from a 20" test barrel.

TOP