Great info Harrison, glad to hear it’s shooting well. 
 

interesting that SIG specs 60 but 65 works better.

i had 2 questonis about steel cores....

am i right in thinking that the only steel portion of current 556 is the tip? apparently it only weighs 19 grains. why didnt they go with a long rod instead>

also, could you get a really long .17 bullet to be made entirely out of steel (if it was saboted), and could you use a really dense steel to bring the weight up to , say, 40 grains?

or is all steel fairly light.

oh, lastly, how would a flechette round do against lvl 4 armour?

take the soviet 3mm flechette.  37 grains, 55mm long, and a energy of 900ft lbs.

smg762 said:

am i right in thinking that the only steel portion of current 556 is the tip? apparently it only weighs 19 grains. why didnt they go with a long rod instead>

Yes, on the M855A1 EPR there is a small hardened steel "arrow" at the tip of the bullet.

They evaluated this design against a PPI bullet made with a longer steel core and a brass sabot, but this bullet design was longer than the EPR and the bullet intrusion into the case was considered too high. The usable powder volume was reduced and the pressure needed to be increased too much to achieve the required MV.

smg762 said:

also, could you get a really long .17 bullet to be made entirely out of steel (if it was saboted), and could you use a really dense steel to bring the weight up to , say, 40 grains?

A really long (spin stabilized) bullet will probably not work with a sabot, so you will need to make an APFSDS. It was trialed during the ACR program and didn't worked well...

SIG sharing updated specs of their 6.8 LMG. Surprised weight isn't listed

https://pbs.twimg.com/media/F3sDoxbawAEXaAZ?format=jpg&name=large

Perhaps more interesting is SIG is advertising its .338 MG as capable of firing a .338 Hybrid; curious what a 80kpsi .338 is capable of ballistically:

https://pbs.twimg.com/media/F3r8B8kawAg9OZA?format=jpg&name=large

gatnerd said:

Surprised weight isn't listed

Perhaps weight will vary depending upon caliber and which buttstock is used, as well as whether or not the XM257 rail (shown below) is fitted?

Here is an older SIG XM250 data sheet (for the 6.8x51mm version) that does list weapon weight:

stancrist said:

Here is an older SIG XM250 data sheet (for the 6.8x51mm version) that does list weapon weight:

I don't know if it's an official document by SIG-Sauer (the German flag looks highly suspicious), as this flyer bears the tag "by Ricardo Torres", and the 4395 J of muzzle energy listed don't fit well with a 135 gr bullet launched at 950 m/s (but 4395 J is OK with a 150 gr bullet launched at 951 m/s, which is exactly what SIG is claiming for the Elite Bonded bullet from a 24" barrel).

YouTube

Future Warfare Rifle Setup? | Noveske 6 ARC Thermal

Many would see this as a "future" rifle setup. Truth is, it is a "now" rifle setup, as enemies both foreign and domestic have individual capabilities much gr...

.

Interesting setup, but they really need to use a different suppressor in order to reduce fouling!

See how heavily lubricated the bolt carrier is before they start shooting, and all the carbon deposit on the gun frame and on the cartridges?

I did not notice how heavily lubed was the bolt carrier, but it was impossible to miss the carbon deposit on the cartridges.

how come the energy is listed as 3200 ft lbs. This is way beyond the 2700 listed for 6.8, and surely its massively overbore too.

in terms of a 7mm magnum for machine guns, could you some how make it work without barrel wear issues?