Someone with Quickload please help! What if: Grendel at 80K psi?

[Fess]

In another forum that I follow (Military Guns and Ammunition), there has been a suggestion that the US Military has realized that it over reached with its NGSW project.* That project did however, generate a couple of interesting technologies like the True Velocity "neck-less" cartridge and the Sig Hybrid case. Supposedly, both could tolerate a chamber pressure of 80,000 psi.

Now that it is realized that the goal of penetrating level 4 body armor at 600m is unlikely with a general-issue infantry weapon and ammunition, the question of "what IS possible" arises. The 6.5 Creedmoor often arises as an option, but the weight savings compared to 7.62x51 is really not that much. It is still considerably heavier than a 5.56x45 system. I wonder what a SUPER Grendel at 80K psi, using the new case technology could do? Has anyone on this forum that has Quickload modeled this yet? I would be interested in the results.

I fully understand that the bolt and barrel extension of an AR15 style weapons would need to be enlarged and strengthened, but that has been done before. In the past, there have been AR15's that could handle the WSSM cartridges (Olympic Arms?), and AR15's that could use cartridges based on shortened 308 cases (AR15Performance, although I know that Harrison has made enemies here).



*They really wanted a cartridge that weighed nothing, had no recoil, and could kill an enemy wearing body armor who was standing behind a tank, two concrete buildings and a fair-sized mountain.

[Lemonaid]

This is from GRT. Not too exciting to me.

[grayfox]

I can get ~2925 with a 123 cup/core bullet, 20" barrel.
3042 from a 6mm ARC, which is ~ 6CM range. 105 BTHP BC 0.527.
At some distance armor penetration would go better I think with a sleeker bullet like 6Arc.
At 600 yds that has 1013 ftlbs ke.

In either case, what we don't know is how the case capacity would change under the new setup - might give more powder room.
And definitely would need to strengthen the bolt/bcg but I think they had to do that for the ngsw too.

I'm also estimating with a 20" barrel so they'd need to go bullpup or just live with a bit longer bbl ... or something.
All GRT estimates.

[Fess]

Thanks. The goal would be mainly reduced weight and bulk while retaining "battle rifle" power. With the development of smart optics, long range performance can become more useful. I recently saw some filmed interviews of Eugene Stoner, who believed that normal infantrymen could not hit targets beyond 300m, so there was no use to have a cartridge that was effective beyond that range. In fact, he was a proponent for fixed sights, figuring that a soldier would not need anything more (and that stressed soldiers tend to fiddle with any available knobs*).

I really don't know if the problem of body armor penetration can be solved with something resembling normal rifles and ammo. Especially since the US wants very short weapons and seems to dislike bullpups. I have seen YouTube videos showing that current M4-style carbines, even using tungsten-cored AP rounds could not penetrate relatively inexpensive Level 4 plates. Penetration of some types of body armor is velocity (or energy-per-unit-area) dependent it seems. Sometimes, however, the rifles with 20"+ barrels COULD penetrate when the 14.5" and 16" could not.

It is possible that a "bullet hose" would be required. In other words, depending upon numerous hits to hopefully penetrate an area with relatively little armor protection. This conjures up images the TV series "StarGate" in which the good guys used P90's and a lot of bullets to get rid of bad guys.



* I apologize for images created in the minds of our non-American speakers of the English language for whom "knob" might also mean a particular part of the male anatomy.

[41bear]

Sorry I'm late to this but am interested in such off the wall thinking. I hit 3000 fps out of a 16" barrel with SW Match using a 100 gr. solid with an OAL of 2.260 at 80,000.