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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NGSW Phase 2 Consolidation and info   Small Arms <20mm

Started 30/8/19 by gatnerd; 520444 views.
gatnerd

From: gatnerd

16/12/21

Thats very interesting. A laymen such as myself would have thought pointy tips would slide through glass more easily and therefore be preferable, but apparently thats the opposite. 

I wonder if the same is true for pistol bullets - whether a flat point FMJ would be better through glass than a typical round nose FMJ? 

Mr. T (MrT4)

From: Mr. T (MrT4)

16/12/21

Pointy tips penetrate better, but as you are never really hitting the glass at a perpendicular angle you want a flat tip for a predictable and much smaller angular deflection when the bullet gets through the glass, the pointy tip is far more unpredictable in terms of how it will deflect when going through glass which might not be that critical when shooting trough car glass as target is very close to the glass , but is quite important when shooting trough building windows where the target could be some distance away.

nincomp

From: nincomp

16/12/21

EmericD said:

The STT-15 rifle with the 18" Proof Research barrel, so they could probably make a direct comparison with the Seekins SP-10 they already use.

It appears that this rifle uses 5.56x45-width magazines.  It will be interesting to see if there are any feeding issues.  Occasionally this is still reported in the 6.5 Grendel forum that I follow.  Perhaps Hornady managed to eliminate the problem somehow with a combination of geometry and bullet choice.   If feeding issues are encountered, I wonder if anyone will bother to run trials with rifles built on the LWRC SIX8 platform.  Although the SIX8 was optimized for the 6.8 SPC, it has a magazine well that is wider and longer than a typical AR15.  

I find it interesting that the US's NGSW program concentrates on improving performance with new platforms and (relatively) high chamber pressures whereas the 6mm ARC goes the opposite direction and utilizes chamber pressures below that of current NATO military cartridges in order to use an older, existing platform.

I find it odd that so much emphasis is still placed on maintaining the bolt and barrel extension diameters of the AR15 when it is now a simple matter to manufacture larger, stronger ones.

stancrist

From: stancrist

16/12/21

nincomp said:

I find it interesting that the US's NGSW program concentrates on improving performance with new platforms and (relatively) high chamber pressures whereas the 6mm ARC goes the opposite direction and utilizes chamber pressures below that of current NATO military cartridges in order to use an older, existing platform.

I find it odd that so much emphasis is still placed on maintaining the bolt and barrel extension diameters of the AR15 when it is now a simple matter to manufacture larger, stronger ones.

None of that should be surprising. 

The US Army can afford to spend the necessary time and $$$ developing completely new guns and ammo.

The 6 ARC was derived from the 6.5 Grendel, a commercial endeavor created on a far more limited budget.

There is simply too little financial incentive to develop high-pressure loadings of 6 ARC for commercial sales.

Mr. T (MrT4)

From: Mr. T (MrT4)

16/12/21

So far all the 6ARC mags i have seen are just 6.5Grendel mags .

Many are branded or rebranded Israeli e-lander mags. I havent seen any realy dedicated 6 ARC mags so far. 

nincomp

From: nincomp

16/12/21

There would be no need to "develop completely new guns."  Several companies have built versions of the AR15 with stronger bolts and barrel extensions: Colt, Olympic Arms, ARPerformance, and CMMG to name a few.  It is not very difficult, given the current state of CNC machining.   Heck, the CMMG "mutant" guns use an oversized bolt and barrel extension for the 6.5 Grendel and 7.62x39 and are in current production.   The 6mm ARC is designed around a weakness inherent in a 60+ year-old platform designed for a less powerful cartridge.  As an engineer, it is almost insulting that so little has been done to optimize something called the "Advanced Rifle Cartridge".  THAT is what makes it particularly interesting.   Note that I wrote 'interesting", not "unbelievable" or "shocking!"    Furthermore, the 6mm ARC is not even anything new, since it is in between the 6mm PPC and 6mm AR both in size and performance.   Those cartridges have been around for a number of years.

A variation of the SIX8 form LWRC with a stronger bolt and barrel extension shooting a shortened 6mm Optimum utilizing SIG high-pressure hybrid cases would be VERY interesting.  The 6mm ARC is a bit ho-hum in comparison.

mpopenker

From: mpopenker

17/12/21

nincomp said:

As an engineer, it is almost insulting that so little has been done to optimize something called the "Advanced Rifle Cartridge". THAT is what makes it particularly interesting

Developing a new cartridge for the existing platform is more or less like putting the cart in front of the horse

First you get a desired ballistic solution for your proposed range of scenarios. Then you design a cartridge for this solution, with desired weapons' features in mind. And only then you start designing weapons for the cartridge

At least, it should be done in that way, in theory

In practice, you get failures like 6.5 Gr or 6.8 rem Spc.

EmericD

From: EmericD

17/12/21

nincomp said:

I find it interesting that the US's NGSW program concentrates on improving performance with new platforms and (relatively) high chamber pressures whereas the 6mm ARC goes the opposite direction and utilizes chamber pressures below that of current NATO military cartridges in order to use an older, existing platform.

The goals were simply different.

The US Army wanted to achieve results that no other portable system could provide, so they needed something totally new.

I think that the 6 mm ARC started it's life as an answer to the question: "what would be the most effective round that could be fired out of a C7/C8 rifle/carbine?" 

nincomp

From: nincomp

17/12/21

Again, I find it interesting that a 6mm cartridge based on the 6.5 Grendel case became popular only after Hornady tweaked it for their own bullets and gave it a flashy name.  Marketing, or Merchandising (as per the clip from the movie Spaceballs) seems to be more important than anything else.  Granted, the shoulder was moved back 0.030" (0.762mm), so it not exactly the same as the various "6mm Grendel" variations like Robert Whitley's 6mm AR,  Les Baer's .243 LBC-AR and ARP's 6mm Predator.  On the other hand, the 6mm AR has been publicly available and used in competition since 2006.

https://youtu.be/HnXKE0nfAjI?t=36

  • Edited 17 December 2021 15:01  by  nincomp
EmericD

From: EmericD

17/12/21

nincomp said:

Again, I find it interesting that a 6mm cartridge based on the 6.5 Grendel case became popular only after Hornady tweaked it for their own bullets and gave it a flashy name.

You probably mean "after one manufacturer standardize a drawing and produce ammo for it?" :-).

The .300 Whisper existed long before the .300 AAC, but the round found a wide acceptance only after standardization.

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