When two rounds of the same purpose (i.e. infantry rifles and LMGs) are shown side by side, apparently in a comparison photo, there is a normal assumption that they will be to scale. 

gat i had 2 questions.

what's the approx. weight of a polymer cased 7.62x51 or 6.8?

did textron's CT round use a plastic case and was it lighter than the others?

assuming a full power muzzle energy, what ME would the 6.8 have at 350meters or so?

random question. what was the weight of GD's rifle? i think i read it was 3.3kg with suppressor, which seems awfully light.

also, if you had a NGSW rifle where the barrel recoiled a long way, like 4 inches, would it reduce recoil more than GDs offering?

smg762 said:

random question. what was the weight of GD's rifle?

Specific answer to your random question:  I don't know.

autogun said:

When two rounds of the same purpose (i.e. infantry rifles and LMGs) are shown side by side, apparently in a comparison photo, there is a normal assumption that they will be to scale.

Tony, I took your question to be in jest.  But if you genuinely do not know whether those two rounds are to the same scale, then I strongly urge you to go immediately to the nearest hospital emergency room.

At my last job, one day I noticed a co-worker was confused about a rather simple, routine matter.  I thought something was wrong with him, but I said nothing.  Two days later he died from the untreated stroke.

stancrist said:

Tony, I took your question to be in jest.  But if you genuinely do not know whether those two rounds are to the same scale, then I strongly urge you to go immediately to the nearest hospital emergency room.

Not in jest, but making a point: those who visit this forum will vary considerably in their knowledge and understanding of this subject, so it is helpful to avoid potential areas of misunderstanding.

smg762 said:

what's the approx. weight of a polymer cased 7.62x51

https://www.reddit.com/r/guns/comments/p542y3/true_velocity_308_weight/

Weight was 294gr with a 168gr bullet.

So loaded with the Army 130gr M80A1 projectile it would weigh 256gr / 16.6g.

But it's lighter than a cartridge would be to get that performance level from a standard pressure case, so technically it's a lot lighter.

Farmplinker said:

But it's lighter than a cartridge would be to get that performance level from a standard pressure case, so technically it's a lot lighter

Yes thats true, and thats the lawyered interpretation SIG is going with and the Army accepted.

And to be fair, its not without merit.

For 6mm CAKE (85gr VLD @ 3000fps) I had envisioned a 6mm HAGAR sized case, but the sig could do it with a high pressure 5.56 case necked up to 6mm. A real weight and volume savings. 

gatnerd said:

       Farmplinker said: But it's lighter than a cartridge would be to get that performance level from a standard pressure case, so technically it's a lot lighter

Yes thats true, and thats the lawyered interpretation SIG is going with and the Army accepted. And to be fair, its not without merit.

I tried to locate the original PON to see what the actual phrasing was, but had no luck. 

The best I found was a TFB summary, which may or may not be a quote from the PON:

     "Ammunition Weight: 20% less than equal amount of conventional brass cased ammunition"

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