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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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NGSW Reset / Change in Direction   General Military Discussion

Started 16-Nov by Guardsman26; 13205 views.
gatnerd

From: gatnerd

17-Nov

stancrist said:

So, if you happen to know the weight of a .25 Remington (or .30 Remington) case, the 6 Optimum case would be a few grains lighter.

Well, we have 6.8 SPC (based on .30 Rem) at ~7.78g per case (depending on brass manufacturer.)

6.8 is 42.3mm OAL, 6mm HAGAR is 45mm OAL, and yours is 48mm OAL, all on the same parent case. 

Lets say +1g to go from 42.3 to 48; seems reasonable and is an easy guess. So 8.78gr per brass case; 3.951g for the TV case based on the 55% reduction.

6mm Hagar 105's are loaded with 29.7gr powder for a target load; for a military (62kpsi) and slightly larger case, lets say 35gr powder. One again just a handy guess here.

6mm Optimum TV guestimate:

6x48 TV Case = 3.951g

100gr Bullet = 6.48g

35gr powder = 2.268g

Small Primer 3.5gr = 0.227g

--> 6mm Optimum TV = 12.93g 

AKA very close to 5.56 brass aka excellent (and also very close to my own goal with 6mm CAKE of replacing 5.56 brass with an equal weight polymer 6mm.)

Gr1ff1th

From: Gr1ff1th

17-Nov

You're not taking into account that you can reduce the powder loading by 15-20% due to the more efficient burn, CT ammo also exhibits this saving, 
 

6mm Revised Optimum TV guestimate:

6x48 TV Case = 3.951g

100gr Bullet = 6.48g

35 -->28 gr powder = 1.8064g

Small Primer 3.5gr = 0.227g

--> 6mm Optimum TV = 12.462g 

When combined with a lighter weight bullet 85gr~ it comes in comfortably under brass cased 5.56, perhaps an approach similar to the Chinese 2 loading system, or even something similar to the existing arrangement of 5.56 DMR's having Mk262 could be explored for further weight and recoil savings, while maintaining commonality


EmericD

From: EmericD

17-Nov

stancrist said:

So, if you happen to know the weight of a .25 Remington (or .30 Remington) case, the 6 Optimum case would be a few grains lighter.

According to data from Nathaniel F, the weight of a .25 Remington cartridge (with a 100 g bullet) is 17.7 g (so, ~11.1 g for a primed case + powder load), and the 6 mm HAGAR is ~15.6 g with a 75 gr bullet (10.7 g for the primed case + powder load), and ~16.6 g with a 90 gr bullet (10.8 g without bullet).

gatnerd

From: gatnerd

17-Nov

Guardsman26 said:

I have received confirmation from an industry source that GD-OTS / Lone Star / True Velocity are now out of the NGSW competition while Textron has voluntarily exited the program.

TV had posted this 14hrs ago on their FB; seems odd to do if they had exited NGSW. 

Guardsman26

From: Guardsman26

17-Nov

It's the GD-OTS gun that appears to have been axed from the program, not TV's ammunition concept. That said, I understand that there are concerns about the accuracy of TV's proposed ammunition configuration. But there is nothing official in the public domain yet. 

The big surprise of NGSW is the performance of the SIG hybrid cartridge case.  Extraordinary strength, lighter weight and potentially lower manufacturing costs all stack-up in its favour. It will be hard to beat. Even so,  Assuming SIG is the winner, TV does not need to say anything before the US Army officially announces the result - although according to the Army's own NGSW timeline, it is now late in declaring a winner. 

We should also remember that companies have an obligation to their shareholders. No vendor will walk away from a potential contract  before an official announcement is made. And even after a winner is chosen, downselected contractors frequently drop the ball after contract award (see UK AFV procurement) so it is in a bidder's interests to maintain a positive attitude.

stancrist

From: stancrist

17-Nov

Guardsman26 said:

The big surprise of NGSW is the performance of the SIG hybrid cartridge case.  Extraordinary strength, lighter weight...

???  Lighter than what?  The SIG case is certainly not lighter than the TV and Textron cases.  I doubt that it's even lighter than the 7.62 NATO case.

In reply toRe: msg 15
nincomp

From: nincomp

17-Nov

Does anyone remember the specs of the .277 Sidewinder round developed by a member of this forum.  It was based on a shortened .30 Rem case, but the case was significantly longer than the 6.8 SPC.  It might have also been longer  than the 6mm Hagar.  I remember that it came very close to meeting early GPC goals (to 1000m) with a lead-cored bullet.  The switch to lead-free bullets reduced its long-range performance somewhat.

Guardsman26

From: Guardsman26

17-Nov

Stan, 

SIG's hybrid case is 10-15% lighter than an equivalent brass case. BAE Systems in the UK is working on an all-steel 7.62x51 mm case that reduces  weight by 20%. 

roguetechie

From: roguetechie

17-Nov

What lighter weight?

6.8 sig saves 20% over the weight of it's "reference case" which isn't 7.62x51.

I understand that people have their favorites and all but pretending like sig actually met the weight savings MINIMUM doesn't reduce the actual load a soldier would be saddled with!

Also, let's just say that I'm skeptical of whether you're not going to see pretty frequent and more rarely very ugly casehead separation malfs and occasional catastrophic kb's.

Im honestly baffled by why anyone would be happy with what sig turned in.

Also, from the cost and strategic materials standpoint, sig's entire system is a nightmare.

stancrist

From: stancrist

17-Nov

Nick,

SIG says their hybrid case is 10-15% lighter than an equivalent brass case.

The trouble is, that's an intentionally deceptive and misleading statement.

The Army sought a cartridge which is lighter than current service calibers.

It means nothing that the SIG case is lighter than "equivalent" brass cases.

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