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; 478295 views.

From: QuintusO


And I really do mean it, for the record. I was very interested in the idea of a very lightweight 5mm round and a high rate of fire (~1200+) rifle to fire it, so I did some pretty extensive modeling of magazines and a weapon, and several studies involving spreadsheets and calculations to determine performance, and guess what, in my opinion the concept didn't shake out. And as is pretty well known here, when I want to be critical of a concept, such as the GPC for example, I try to actually put it through its paces and represent it properly. This fair and analytical treatment is probably why Romulan v Vulcan was so convincing to many people who had previously considered the GPC idea sound (granted it took me several tries to create a study that convincing). I represented the idea properly, and thoroughly and fairly investigated it against other concepts. Which, if you don't want these discussions to be on a "nuh uh Batman can totally beat Superman" level, is what you probably should be doing.


From: EmericD


roguetechie said:

Feigning ignorance when the brevis 2 has been discussed here many times is a bad look by the way.

I'm not "feigning ignorance", I was just told that SOCOM was using Surefire suppressors, and the USMC recently selected KAC suppressors.


From: EmericD


QuintusO said:

I mean this really does come off a bad faith reply. Roguetechie may be very contentious, but he at least made reference to all the sources he was using. Coming back with "Oh YEAH? Well have you PERSONALLY tested it?" comes off as missing rogue's point, deliberately, just so you can throw some weight around.

No, that means that I don't buy the manufacturer's claims, or the manufacturers claim that his product was the "C" product found in one official report.

There is a report on TBF, but it's not really sustaining the points made by Roguetechie.


From: poliorcetes


What does YOLO specs mean? I know YOLO from computer vision (a library beyond any awesomeness), but I guess it is not related with "You only look once"


From: DavidPawley


You Only Live Once

In this context: what the hell, give it a try, no limits.


From: stancrist


Since they have already taken a shot at meeting the original specs,

"You Only Live Once" seems inapplicable to making a second effort.


From: QuintusO


Is there a problem with just saying that? "Yeah, I am not sure I buy their claims." That's sort of my point.


From: gatnerd


QuintusO said:

So 7-15 oz of extra barrel is fine, but 7-15 oz of suppressor at the end of a barrel is bad.

In the context of the NGSW purported goal of penetrating Level IV armor, barrel length is far more valuable then suppressors, simply because the velocity requirement is so high for defeating armor. 

In this video of M993 - at 3016fps, M993 defeats armor. At 2867fps, the armor stops it:

Thats essentially the difference in velocity between SIGs 6.8 out of 13" vs 16".

Further testing from Buffman against other plates has shown small velocity differences to be make or break for armor penetration. Heres the ESAPI:

2795 avg = Penetration; 2612fps = no penetration. Thats a difference of 183fps - about equal to the +150fps the SIG gains from going from a 13" to 16" barrel. 

Barrel length is not the end all be all for most cartridges ( 7.62x39 and 6.5 grendel have most of their performance out of 12.5" barrels and thats what I'd issue; 5.56 14.5-16".) 

But for NGSW, armor penetration is going to live or die by velocity. And whether the cartridge is 60kpsi or 100kpsi, a few inches of barrel length can make all the difference in armor penetration. 

In terms of weight, the difference between a 13/14" vs 20" barrel is equivalent to the weight of a Titanium Brevis, but much less then the weight of a more conventional suppressor. 

Scar 17 13” = 7.7lbs

Scar 17 16.25” = 8lbs


+3.25” = .3lbs / 4.8oz  / 1.477oz per inch


Scar 17 20” (assumption based on above) = 8.37lbs


13” vs 20” = +10.34oz

Brevis 7.62 Titanium = 10oz

SIG SRD 7.62 = 17oz

Surefire SOCOM 7.62 = 21oz

Thales F90

360mm/ 14.17” = 3.15kg / 6.94lbs

407mm/ 16” = 3.25kg / 7.17lbs

508mm/ 20” = 3.39kg / 7.47lbs


14”->16” = + 0.23lbs / 3.68oz

16” -> 20” = + 0.3lbs / 4.8oz

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From: roguetechie


Not all 65k or 100k psi events are equal though.

That's my first thought but it's not my only one or most important one.

You're very right in that muzzle velocity is incredibly important in determining whether or not we accomplish our goal here.

Where you're wrong though is that the extra few inches of barrel length is far more valuable than a can and it's because you have left out a critically important factor.

Muzzle pressure.

Put very simply, in the case of the 6.8 ngsw rounds it's going to be downright unsafe to the end user and the people around him to be firing from a bare uncanned muzzle.

When you fail to take into account a factor which completely negates what you are proposing you will come to unusable conclusions.

This is a classic GIGO situation. The reason you haven't seen these guns shooting uncanned is because it's not a good idea to run them that way.

Once it becomes clear that you need some sort of can more or less no matter what because of the inherent qualities present in the 6.8 round, you realize that you need to put consideration into things that are actually options.


From: QuintusO


Oh so you're saying it would be nice to have some way to have the benefits of a suppressor, the weight and length reduction of a shorter barrel, and still retain high velocity, and that you think it makes sense to put some effort into achieving all of that?


  • Edited 11 August 2021 17:43  by  QuintusO