@spydercomonkey  Good info, Thanks

I agree with some of this, 6.5cm is a damn good round. But perhaps they are considering Sectional density and energy on target?

Most PRS rifles are using Bartlein stainless, cut-rifled, and they are known for one of the harder, longer-lasting stainless steels similar to Krieger.

The 7.62 NATO cartridge is very forgiving on barrel life, so making any corollary assumptions about how a .270 Weatherby Magnum +P pressure cartridge will do with the flow-formed exotic alloy barrels is assuming a lot.

Even if they do achieve a reasonable barrel life, the performance metrics have been all over the map on this project, which indicate a degrading acceptance of reality and their failure with bore diameter and projectile selection.

125gr at 3400fps from a 16" barrel
135gr at 3100fps from a 14" barrel
135gr at 2800fps from a 13" barrel

Another pic of a Sig carbine looks like they really did do .270-08:

M80A1?

There's only 4 companies entering and 3 of those companies are using a standard cartridge layout. Textron of course is using their LSAT, which the diameter of the cartridge is incredibly large at like .56" or so, so you still run into the bulk issue.

There's really no way around a bulky gun when you need a 135gr 6.8 to be slung at 3,000 fps from 16" or less barrels.

FN is looking to submit a modified HAMR variant.

No matter what, we're going back to .308 or larger size guns.

I doubt we move back.  More likely it dies on the vine like most the other projects.

Yes, which a .600+ G1 BC projectile will do better than compared to a .500 G1 BC even when the .500 G1 is fired faster.

There are 125gr 6.5mm lead-free AP projectiles well over .600 G1 BC.

A 120gr tipped 6.5mm lead free bullet is as long or longer than most 140gr cup and core high BC bullets.  Most of your 140gr and above cup/core 6.5mm are in the low .600 G1 BC and up region.

There's a 131gr .257" bullet I've been working with that has a .330 G7 BC, or somewhere in the .640-.655 G1 region.

Defeating armor is a function of energy and sectional density plus construction.

You want as much speed, as much SD, and as dense of a penetrating material as possible (tungsten, hardened steel, DU, etc.).

The larger you go in projectile diameter, the heavier the bullet has to be to keep the BC high.

Keeping the BC high helps with speed retention for impact on-target.

Why they insisted on .277" diameter was based on a combo of the above, but I assert that it can be done with .257 and 6.5mm, with less penalties for the shooter in a heavy weapon, that also has insane recoil.

If it were me, I would be looking at the .257 and 6.5mm options more closely and not messing around with .277" 135gr magnum +P pressures.

One of the more interesting things to me is who is NOT submitting in this competition.

Hk

That tells me a lot.

Dude, we aren't going back or going bigger. The only reason 308 and larger is considered is because of Afghanistan. We wont be there much longer, and most likely our next best candidate of theater is Africa and the south china sea where the 556 will do just fine. Also what if we get into a situation with megacities? You gonna clear rooms with that beast, haul all that up 60 flights? I wouldnt want to fight in stalingrad conditions with that. We are not going to have a near peer adversary and if we do, small arms will mean jack shit, air power is everything. This is all retarded.

Yup

We have reached the bow and arrow of our age. Firearms will remain relatively unchanged for the next 100 years would be my guess

It's getting sporty now.

The concept is interesting. But I don't think we'll get there via conventional means.

The monkey in the tree is who made up this mythical 600m engagement criteria? Last range I went to, about 9 years ago, people would intentionally NOT engage the 300m targets and save those couple rounds as alibi shots if they missed the 250m and less. So now Joe Schmuckateli is going to engage 600m targets? Units might get to the range 2 times a year, if they are CA units, as it is now but everyone is going to be proficient enough to be killing at 600m? Besides the weight of this new uber round and the increased weight of the rifle/LMG that fires it, you need to add in the optic that will allow these 600m engagements. Don't forget replacement costs for the optic either, you know for those time Joeshit the ragman drops his rifle off the top of a Brad or slams it in the door of the new, equally worthless, JLTV.

Okie dokie then. That's the perfect range to start engaging a "near peer", perfect for their indirect fires.

We fight wars drastically different on the ground now. The average soldier has many more responsibilities than the average WW2 infantryman. The battlefield is totally different. And, although neither you nor I could provide any objective evidence to support our cases, I would argue the American soldier and Marine are far stronger, better conditioned, and tougher today than at any point in our history.

87 days after it is adopted as the new standard we will have new Level V armor that defeats the new round.

The US Army has a long and storied history of running next gen small arms weapons programs coming out with neat concepts running a competition then deciding the juice isn’t worth the squeeze. I wouldn’t hold my breath if I were you.

The 80s/90s one with colt duplex rounds a steyr bull pup with polymer cased sabots, the landwarrior stuff with the OICW, the xm8. Old forgotten weapons stuff between krag and 1903 Springfield, completely changing the m1 garand from .270 to 30.06 at the last moment etc....

Seems very premature and myopic to be certain a) this shit will go anywhere or b) this particular entrant will win if this shit goes anywhere.

Yup, good stuff. I've watched that when the video was first made.

There is a reason Qualification scores went up when we adopted 5.56 over .30 caliber rifles. It is the most balanced round when you're trying to combine a very easy to shoot round that is also very effective. In fact, there were lethality tests that showed 5.56 was more lethal than the .30 caliber rounds. And lets face it, the M16/M4 is the most baseline, bottom tier weapon in the military. When are Infantry unit goes out, they usually do or should have a bunch of tools at their disposal that far exceed the range and lethality of a rifle cartridge. Yet the retards behind these trials are looking at war from a rifleman vs rifleman perspective. They're the same kind of morons who say if Germany had only come up with the StG44 sooner, they'd of beat the Soviet Union.

The only logic I can see in going to that extreme is to have overmatch on future armored threats.

Lvl 5 comes out but the current rifle can still defeat it at a reduced range. Ie 300m vs 600m

It is a soup sandwich, that much is sure.

Thats why they put the smallest stock magpul makes on it.

Many thanks for a straight answer to my question.  Some times, questions receive snarky replies from a basement dweller who know the intelligent answer.

In some of my closed DM courses where units have brought both the 7.62 NATO and 5.56 systems, we do some fun culminex drills at the end on a shot-timer.

One of the ones we've done just for fun is a plate drill, maybe 6 plates coming up out of cover and concealment.

With many years of competitive and training experience on a shot timer and with accuracy standards, I can still easily beat myself with a 5.56 or 6.5 Grendel compared to 7.62 NATO, and any recoil or muzzle climb mitigation devices I use on the 7.62 also can be used on the other calibers.

Yup, logistics and industry dont do a damn in warfare

if you're basing this off of produced cartridges, ok. If you're basing this strictly off of bullet diameter alone,

Yep, 7mm is a poor choice for the same reason 6.8 may be a poor choice.

I tend to think a 6mm would be a better choice than 6.5 or 6.8 - if you can get the velocity up in a short enough barrel and not burn barrels too fast.

Lmfao that sounds hilarious.

Got a link?

.257" has been overlooked for decades and the Army's own studies over the years have shown that an ideal shoulder-fired rifle cartridge would have a 6.35-6.5mm diameter when looking at retained energy as well as recoil.

With .257", you can still have controllable fast shots for CQB without much of a signature over 5.56, and you can have a smaller case volume than 7.62 NATO, closer to 5.56 NATO.

It and 6.5mm also make excellent Sniper, DM, and Machine-Gun diameters.

I shot my 270 WSM today.

No way that will go to the current crop of privates to shoot in basic training.

It is very snappy in a bolt gun but man it hits steel with authority.  I am going to do that more at 600 yards just for the satisfaction of the gong.

You have a good point but in some cases they were:





https://history.amedd.army.mil/booksdocs/wwii/woundblstcs/chapter11figure330.jpg

https://olive-drab.com/od_soldiers_gear_body_armor_wwii.php



Body armor that apparently belonged to an American soldier during the Korean War was found at a site in the DMZ during a search in spring 2019.

I posted this link earlier, but no one seems to have watched:

https://www.youtube.com/watch?v=ND9nn4oCIbg

We already have 'defacto Level V' armor on the civilian market that is capable of stopping Tungsten AP 7.62x51 @ 2850fps from 40 feet away.

I would be amazed if this 6.8 round could defeat the same plate beyond 100m today, much less the absurd claim of 600m.

Given the pace of armor tech development, its entirely possible the new 6.8 round would be able to be stopped point blank within the next 5 years.

Why this matters:
-Our current and most plausible future enemies don't wear body armor, making this 6.8 pointless
-By the time we get around to fighting armored enemies, armor will have been developed that renders 6.8 ineffective
--> It's a terrible idea

The underlying technology being developed in this program is worth pursuing (lightweight cases, smart optics, new barrels, lighter machineguns, low drag projectiles) but its should be implemented in much less powerful cartridge.

An example is a 6mm 85gr VLD @ 3,000fps. Using polymer cases, you'd have a round that weighs as much as brass case 5.56, with the recoil of a 7.62x39, and the effective range of a 7.62x51.

The only difference is the projectile and the equipment and tooling already exists. Its just sig being fucking stupid

You realize the army said here is a projectile. We want weapons systems to launch it x for y lenght barrel. How you do it, we dont care.

Nothing about prior art really makes sense to pursue. Make a cartridge optimized to work in your system and meet the criteria.

There are so many dumb assumptions in this project.  They should take another look at that .338NM mg.  That thing has range and power to spare without all the infrastructure needed for an M2.  Assuming small arms will mean anything in a near peer fight.

A tank fires a bit fewer rounds than an infantryman's carbine. So while its tube has a short barrel life, it lasts rather long in time.

Its also absolutely critical, because while its not awesome having to rebarrel a main gun, that gun is the only thing that can both easily kill a tank or blow up a building, bunker, etc. Is the 6.8 125 gr at 3-3,400 fps absolutely critical to kill enemy dismounts wearing 10x12" chest plates?

Imagine T72 tank was made out of plastic, except for the glacis and rear hull. The turret, manlet, sides, etc, all are plastic. Do you think we'd have investing in a high velocity 120mm canon, with a short round count, firing depleted uranium sabots to deal with mostly plastic enemy tank? Hell no, we'd just don't aim at that small bit of enemy tank that is actually armored.

Too bad crunchies can't figure out what us tankers have had to consider since WW2.

I've heard in order to engage a man sized target at 600m. You have to shoot a grouping the size of a quarter/25 cent piece and keep every round on there. Which is quite a challenge for most people, let alone when you're using ammunition that is general purpose 4MOA stuff.

There was a thorough study the British Army did back in the day, when marksmanship was extremely important in Army's all around the world. And the British Army was especially well known for their good shooting abilities. And they tried to see what was the most practical engagement distances when you're going up against enemies that using camouflage and shooting at you from cover, or using concealment, or laying in the prone, ect ect. And they found even their world renowned Infantry had a really tough time engaging anything out past 150 meters. I can't point to this study... I learned it from watching one of Ian McCullom's videos where he talked about that study, so I defer to his expertise.

A 1" group at 100m translates to a 6" group at 600m, plus wind deviations.  So it's more like you need to hold ~3MOA to hit at 600m.

I'm not going to say it's easy in a field environment, but you can certainly put aimed fire in place and if your decent score hits as long as the wind isn't bad.

ETA: Camo, cover, concealment and movement will of course make it more difficult.

You don't seem to understand BC.

Please follow along.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

BC is critically important in a penetrator round.  The longer you hang to velocity, due to a higher BC, the further your ability to penetrate armor is extended.

What we are dealing with here is a projectile problem.  The Army is too stupid to understand BC, which is why they feel the need to propel a 120gr. something grain 6.8mm cartridge from something like a .270 Weatherby Mag.

IF the BC wasn't so bad, they would not need this much cartridge to propel it.

From reading one of LRRPF52's posts, the BC for this new 6.8mm bullet is in the same ball park as M8555A1!  A G1 BC in the low .3 range.  That sucks even worse than I thought.

There are off the shelf 6.5mm bullets in the 120gr. range with G1 BC's in the mid .6s.

The 3/8" of armor penetration by the M855A1 is achieved up to 350 yards, which equates to an impact velocity required of about 2,000 FPS or higher.

Say they both start out at 3,000 FPS.  For the sake of argument we say this new 6.8mm projectile has the same penetration characteristics as M855A1.

This 6.8mm reaches max penetration distance or about 2,000 FPS at 350 yards.

The off the shelf 6.5mm reaches max penetration or about 2,000 FPS at 725 yards.

At 300 yards the 6.5mm bullet has less than half the wind drift due the massive BC advantage.

The 6.5mm will also reach the target with only 60% of the drop of the 6.8mm projectile.

The difference in hit probability between the 2 is insane.

The whole issue is whoever wrote the proposal either doesn't know anything about guns or it's pork barrel procurement designed to make money and fail.

Punching level 4 plates at 600M with a 6.8mm projectile is a non-starter.  With the G1 BC of about .31 this will need a muzzle velocity in the region of 3,900 FPS!

To have a faint chance with their fairy tale .270 WBY Mag cartridge, the barrel would need to be around 24 inches and even then it will fall far short.

These morons want to try with barrels in 13"-16" range.

To achieve the penetration specs, with those barrel lengths and this projectile it will need to be a 270-30-378 Weathery Mag.

It will NEED a muzzle brake.  Did anyone say muzzle blast.

We are talking long term hearing damage being around that being fired once without ear pro.

Most people can't even shoot a .308 AR well.

Let alone a 270-30-378 AR, with a firing signature visible from space.

Meanwhile, lighter 6.5 CM ARs from Savage and the DPMS GII line could come close to meeting their design spec, due to the BC available in off the shelf 6.5mm projectiles.

TL/DR: The design spec is retarded. 12-16" 6.5 Grendels with S&B 1-10 optics would make WAY more sense.

Right in a weight in the 170gr. - 190gr. range.

Which means to propel that about 3,000 FPS you need something with the case capacity of a 300 Win Mag.

Now put that in a gas gun.



6.5mm bullets in the 120-140gr. weight range can be propelled in the 3,000 FPS range with some in the .308 case capacity range.

In a semi / fully auto rifle, even something based off 6.5mm bullets and the .308 case is still too big for even the guys in CAG to carry.

My dislike of 6.8mm projectiles is based on the math alone.  Interesting you think math is retarded.

6mm - 6.5mm Grendel type option makes a lot of sense.  A normal person can actually carry a gas gun in these chamberings and they work well in shorter barrels.

From what I understand, the BC of the 135gr .277" projectile is over .500 G1.

They started with a 125gr .277" projectile that was to go 3400fps.

Then they switched to a 135gr projectile going 3100fps.  That's what you would get with max loads in a 26" .270 Winchester pushing 130gr solids (65,000psi).

Not the round itself. Posters here were certain we would get battle rifles for BCTs, but alas.

https://nationalinterest.org/blog/the-buzz/the-us-armys-powerful-new-762mm-service-rifle-officially-23472

Ash Hess and leaspeed6 on the IG

Which still loses 100-150 yards of penetration to 120gr. 6.5mm.

The 6.5mm also enjoys a 20% better hit probability.

6.5mm can do this from a .308 case capacity levels.

Realistically these guys are going to smoke barrels in way less than 1,000 rounds.

We are in agreement as to the stupidity of the idea.  Thanks for the data and info.

Came for gun porn,

Left with PhD in metalurgy, projectile physics, and military logistics.

I feckin love this place.

I'm glad General Milley has got those guys at Picatinny solving this.

We couldn't figure out how to get around the laws of physics and thermodynamics when I was in.

The 270WSM can get 3300 with good handloads using 130s.  I don't know of a 135 in .277.

Anyway you look at it they want this cartridge to be a stout one.  No way a normal barrel will last long at all.

Just silly, this will go nowhere.  You would think the Army thinks it is 1890 or something.  I wonder if it will come with volley sights too.

I mean, it's the same person pushing the program as that one.

Top Men.

@spydercomonkey

The real leap will be when they start applying reactive armor concepts into personal body armor. Plenty of vehicle already have armor that is designed to move in reaction to an impacting projectile in such a way to keep it from punching through, and it's not all just explosive reactive armor. How long until they scale that stuff down to make a chest plate that reacts to a bullet like an airbag, with stored chemical energy pushing against the projectile with high-velocity foam, forcing it to tumble sideways and shed velocity before it strikes the ceramic/steel composite back plate? I think the right way to go with this is to train people to aim for heads and groins when needed, since that's what they'll need to do anyway once we inevitably start adding the term "Level 6 Body Armor" to our vocabulary.

They should just procure an 11.5" AR in 5.56 with a free-floated quadrail, two-stage trigger, and QD shorty suppressor and call it the M4a2. Then maybe a DMR/SPR upper with an 18"-20" barrel and a LPVO, and that KAC LMG with the constant recoil system. Forget about merging the carbine, DMR, and LMG into one gun.