This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.
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The folks at Battle Order have joined in.
Nice, I love their posters.
Watching this interview on SIG's 6.8 ammo:
-Cases currently running "mid 70's" pressure aka around 75kpsi
-Claim the cases can be run to 120kpsi should the future require it
Man, thats worse than what I said.
Gotta love SIG.
I agree with Emeric. A standard pressure 6.8x51 mm NGSW must be VERY close in performance to 6.5 x 49 mm Creedmoor. I believe SOCOM has its own 6.5 mm EPR-style projectile that is identical to the 6.8 mm NGSW projectile in terms of profile, but weighs less - 6-7 grams. A 6.5x49 mm CM fired at standard pressure (55,000-60,000 psi) has the advantage of weighing 18-19 grams versus SIG's 6.8x51 mm cartridge at 21-22 grams. You can also use the 6.5 CM lower chamber pressure to engineer a polymer case to deliver a lower weight cartridge, close to 16 grams.
Emeric, I am not a ballistician, but what do you estimate would be the chamber pressure of a 6-7 gram 6.5 mm bullet fired from a 6.5x49 mm Creedmoor cartridge at 3,000 fps / 914 mps?
Second pint, popped primers with FN SCAR are due to some manufacturers using soft metal primers, not military spec ones. SCAR is designed to meet very demanding military standards. It is designed to achieve 1 mm of penetration for military spec 7.62 mm and 5.56 mm cartridge primers. With soft primers it is achieving 1.5 mm or 2 mm. The latter is obviously too much. I know this, because I was on the range with FN today, and asked their technical lead. (I was firing Evolys in5.56 mm and 7.62 mm ).
I agree with Emeric. A standard pressure 6.8x51 mm NGSW must be VERY close in performance to 6.5 x 49 mm Creedmoor. I believe SOCOM has its own 6.5 mm EPR-style projectile...
Upon what do you base that belief? Emeric said that SOCOM does not use EPR projectiles.
I believe SOCOM is experimenting with EPR projectiles.
That does not answer my question, but I would be extremely surprised if SOCOM is not developing both EPR and Tracer rounds, as they will be needed for the 6.5 CM LMG.
I wonder if there will be issues with developing a tracer that will match the trajectory of the high-BC bullets normally used in the 6.5 Creedmoor (and 6mm ARC, for that matter). It may be easier to match the trajectory of less-dense EPR bullets than to match lead-cored ones.
It has occurred to me that the mediocre BC of bullets used in cartridges like the 280 British and 6mm SAW might have had more to do with limitations of tracer rounds than ball ammo.
I wonder if there will be issues with developing a tracer that will match the trajectory of the high-BC bullets normally used in the 6.5 Creedmoor...
Good question. Perhaps it just requires experimenting with bullet weight and muzzle velocity?
7.62mm M80A1 Ball and M62A1 Tracer reportedly both weigh 130 grains.
5.56mm M855A1 Ball is 62gr, but M856A1 Tracer is much lighter, at 56gr.