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Old October 17, 2018, 09:56 AM   #126
Bartholomew Roberts
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On another note, depending on projectile material, you might see some interesting BCs. An all copper 125gr would be fairly lengthy. In the soldiersysens link, Milley says that the projectile will “probably” be 6.8, so apparently 6.5 is in the running still.

Still, you are basically reducing ammo load and shooting a harder recoiling round. Unless you upgrade your ability to hit with the rifle significantly, you are going to lose capability. Fewer rounds will hit to begin with and you’ll have fewer rounds to shoot. Unless the new optic has overturned Hitchman’s 1950s observations, that seems like a good probability.
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Old October 17, 2018, 10:14 AM   #127
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Personally, my bet is that the US will still be using the 5.56 as its primary military round in 2050.
I'll take that bet.
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Old October 17, 2018, 10:17 AM   #128
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Personally--I think the answer already existed a long time ago in a galaxy far away when FN presented their .284 T48 shortly after WW2.

https://www.youtube.com/watch?v=mby4hOq-DpI
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Old October 17, 2018, 02:57 PM   #129
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One of Ackley's books has a chapter by the doctor who worked the livestock trials of the .276 Pedersen, doing autopsies on pigs and goats. He didn't think much of the .276 itself but there was an experimental .256 Pedersen that was very deadly.
Note: .256" is the BORE diameter, groove and bullet diameter are .264".

I had great hopes for the plastic cased telescoped cartridge guns. Textron who was working on that is a contractor for the current program.
I think something like this is needed, tweaking the metallic cartridge Just One More Time at huge expense may not be the best way to spend the Army budget.
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Old October 17, 2018, 03:48 PM   #130
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Note: .256" is the BORE diameter, groove and bullet diameter are .264".
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Old October 17, 2018, 04:33 PM   #131
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For the military, I doubt we will see all copper projectiles...

We likely won't see lead cores going forward either, not for rifles anyway.

The current m855a1 is copper with a steel tip.

Such a design will sit somewhere between lead core and all copper, for length to weight.
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Old October 17, 2018, 04:36 PM   #132
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Unless you upgrade your ability to hit with the rifle significantly, you are going to lose capability. Fewer rounds will hit to begin with and you’ll have fewer rounds to shoot. Unless the new optic has overturned Hitchman’s 1950s observations, that seems like a good probability.
So long as the notion of fire superiority is used in the battlefield, ammo quantity on hand will be an issue and as you note, soldiers carrying larger rounds will have less ammo.

In reading numerous books on the Gulf wars and war in Afghanistan, a pattern that I see repeated time and time again is that when soldiers come under attack, they attempt to establish "fire superiority" by shooting as much as possible until somebody realizes they are getting low on ammo and they are told to conserve their shots. If it had not happened already, somebody will have been on the radio doing everything in his power to bring in air support to cover for the ground troops before they run out of ammo, and to resupply if extraction is not possible.

In other words, quantity on hand really matters given current military field tactics. Either the soldiers will have to increase their load, OR, tactics will have to change. You can't keep the same load with current tactics.
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Old October 17, 2018, 07:04 PM   #133
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Not to mention that a super-velocity cartridge in a 16” barrel is going to be limited in rate of fire as well. We’ve had several discussions here about the Battle of Wanat where 3 SAWs and several M4s went down to heat from the high rate of fire (and one M60 ran out of ammo entirely).

If you are burning up 5.56 SAWs, I think you’ll be in real trouble with a 125gr travelling 3,500fps in a 16” barrel.

I’m really interested to see how the Army has overcome some of these really daunting engineering problems.

ETA: For that matter can you imagine cutting loose with an M855A1/M80A1 type round of 125gr at 3,500fps in an urban area? That’s going to dramatically increase the risk of collateral damage.

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Old October 17, 2018, 07:51 PM   #134
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Yeah... That's a lot of energy at that MV and weight.

Way too much for a combat carbine. Problems with handling and with collateral as you say.

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Old October 19, 2018, 01:54 PM   #135
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Ref. Post #130: Bore diameter is the groove diameter. Lands stick out to the inside of the bore.
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Old October 19, 2018, 06:06 PM   #136
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Interesting discussion on how this solicitation relates to the NGSAR solicitation:
https://www.thefirearmblog.com/blog/...sw-not-reboot/
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Old October 20, 2018, 09:36 PM   #137
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I love reading threads like this, I always learn a ton from you guys/girls/gender neutral word...

Correct me if I'm wrong, but velocity of the projectile is arguably the most important aspect of defeating body armor. Is that why when discussing an increase in size of the projectile, it is talked about keeping it at current 5.56 velocities (or exceeding it)? There is an old video on the MAC channel where he shoots at a tree with different calibers and if I recall the smaller/faster rounds beat the larger rounds (i.e. I believe 5.45 beat out a 7.62x39 and possibly 308, don't remember exactly). Yes I know a tree isn't body armor but I'm just thinking of penetrating effectiveness.

On a side note: that LMG made by Sig, looks like something Sig would make because it looks like all their pistols... Normal grip, small looking trigger guard, HUGE BLOCK OF METAL ON TOP. It just looks like the pistol grip and the rest of the gun don't belong together IMO
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Old October 21, 2018, 01:20 PM   #138
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Yes... Velocity is very important for armor penetration.

Steel targets as an example... A half in thick plate can handle up to 3000fps, a 7.62x39 is fine, but a 30-06 will blow through easy.

In general... Penetration is a function of momentum. Adding velocity is an easy way to get that momentum. In hard armor, velocity is needed to get through before the softer projectile material can deform and spread out the transfer of the energies.

Mass adds inertia, which is a helpful aspect as well, but for different reasons.
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Old October 22, 2018, 11:35 AM   #139
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And that’s why the 6.8 for this cartridge won’t be The 6.8 SPC.
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Old October 24, 2018, 09:03 AM   #140
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David's right to the extent my reflections are just an armchair quarterback's--but then that's part of the reason we have this forum--else he can hang out on a "for operators only" forum if the "who swings the biggest pair in the jungle" is what he really wants to establish. It's for that reason I make it clear that I'm not an expert with any real experience in every post I make.
Not even close. I simply related my experience doing what I have done most of my adult existence for a living.

Just as you bring your experience, I brought mine. Obviously quite a few people are threatened by that. Some remind me of the wives who claim to have special knowledge or insight. Even one member who decides he knows more than the selection board. Pretty impressive...

It is not my issue. Nor do I have any desire to correct the internet or get into it with a forum clique.

Looks like you guys have had a great discussion and I will leave you to it.


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Old October 24, 2018, 11:30 AM   #141
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Well... That was civil.

The experiences had on a battlefield don't directly apply to civilian and LE situations. That's the basic jist of it. The problem has never been with what you have seen, only the assertion that such experience translates to a blanket statement about 5.56 on the whole.

M855 is a very poor performer, that's not in dispute... But civilian and LE testing and experience has shown that 5.56 can be effective... It wasn't until the Mk262 and the mk318 that terminal performance was getting to a decent place, and those where not in widespread use across all troops from my understanding.

Making 5.56 effective with a bullet design that fits the limitations on battlefield ammo, and that can perform well in many situations... That's difficult. You have to consider ranges beyond 150yds, light armor, barriers like walls and doors, heavier barriers like cinderblock, ricochet potential, possible use in short barrels (12" or less)... And on top of all that, it needs to have good terminal performance as well. (Likely a few more things I forgot, or just failed to mention)


Thinking about penetration from before...

The physics are interesting...

For hard materials velocity is most important to penetration... Mass is important too, but to a lesser degree. Velocity can compensate for lower mass in that situation. Eventually you can hit a point that even very small and light objects can blow through and even leave a disproportionately large hole.

It is all interconnected though. The thickness of the material is also an important consideration... And sometimes simply "Moar Speed!" Isn't the answer or is just not feasible, so then a bit more mass at the same speed or a more efficient projectile shape is in order... Or even possibly a change in projectile material that has a higher resistance do deformation, allowing the projectile to not deform and dissipate as much energy getting through.


For soft materials it's a little different.

As a projectile moves through a soft medium (like a large sack of mostly water) drag looks to slow it down. You lose velocity, and the momentum it brings. Mass on the other hand is basically fixed... (in a projectile that does not break apart) So the inertia and the momentum component the mass brings, will stay the same. So more velocity isn't always going to help... As it can unintuitively sometimes lead to a more rapid loss of velocity through the medium.

This is a big part of the functional mechanic behind hollow point ammo. It is the reason why that for the same projectile weight and type (say 124gr 9mm Federal HST bullets) the standard pressure rounds often penetrate deeper than +P versions. More velocity means quicker and a bit larger expansion, which increases the drag experienced by the projectile, leading to a more rapid loss in velocity, therefore less overall penetration. In fact, I suggest standard pressure loadings because of this. The more rapid expansion, and the fact that total expansion is not significantly more than standard pressure, not that it matters anyway... Shot placement and penetration are king and queen for handgun performance... For rifles, this matters too... Varmint bullets can perform better terminally from short barrels, due to lower velocity delaying the expansion and breakup of the projectile.
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Old October 24, 2018, 02:50 PM   #142
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^^ i agree 100% with the above.
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Old October 24, 2018, 03:59 PM   #143
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Personally, my bet is that the US will still be using the 5.56 as its primary military round in 2050.
The only reason for 5.56mm is logistics. It is the NATO standard infantry round and changing that is not impossible but definitely expensive.

That the Army would independently abandon that after its battlefield experience in the GWOT and formally begin its own adoption process for 6.8mm speaks volumes about the effectiveness of 5.56mm.
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Old October 24, 2018, 04:17 PM   #144
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That the Army would independently abandon that after its battlefield experience in the GWOT and formally begin its own adoption process for 6.8mm speaks volumes about the effectiveness of 5.56mm.
Only from a Mil perspective. The point you keep missing is the effectiveness of non military loading in civilian SD/LEO usage.
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Old October 24, 2018, 06:17 PM   #145
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The stated purpose (according to Gen. Milley) of this ammunition is to “penetrate any existing enemy body armor.” Considering that modern body armor is capable of stopping 7.62x63 M2 AP at 10m, this isn’t just a caliber change.

As DNS alluded to earlier, this is a repudation of the entire idea behind an intermediate cartridge and assault rifles. The cartridge Gen. Milley is discussing is even more powerful than the full power rifle cartridges of WW1. Tactics wise, it would be like the ideological shift from trench warfare to mobile warfare.

All that assumes this is actually implemented instead of XM8, XM25, G11, ACR, SPIW, and a dozen other “next generation” infantry weapons that fizzled out.
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Old October 24, 2018, 07:58 PM   #146
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He says its the offspring of a project formally known as the Enhanced Rifle Cartridge Program that combined Special Operations Command, the Army Marksmanship Unit, and Remington Arms to create an alternative to the 5.56mm round currently in use.

The 6.8mm falls in the sweet spot that the Army is looking for—with all the positive aspects of the 7.62mm NATO round, but with more lethality and accuracy. The new ammo also saves about 10 percent in weight—an important consideration for a combat load.
https://www.range365.com/us-armys-my...new-68mm-round

Quote:
Given past acquisition trends, it is highly improbable that NATO would adopt a new cartridge unless the US armed forces, and the US Army in particular, intend to field it in significant quantities.

US Army requirements are thus the most critical factor in determining whether a general-purpose calibre is likely to be adopted by major Western militaries.
http://www.smallarmssurvey.org/filea...chnologies.pdf

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JOINT SMALL ARMS TECHNOLOGY
DEVELOPMENT STRATEGY
FOR
JOINT SERVICE SMALL ARMS
SCIENCE AND TECHNOLOGY
INVESTMENTS
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The JSSAST Top 50 is a Joint Services prioritized listing of the small-arms deficiencies that the services are requesting S&T to address in any way possible
Quote:
Opportunity Areas (from Table 7-1) Items 2 & 19 deal with engagements in Close Quarters Battle (CQB), ranges less than 50 meters.
Quote:
2. Engage Threat Personnel with Small Arms Fire from 0 to 50m
Quote:
19. Engage Threat Personnel with Precise Small Arms Fire from 0 to 50m
http://www.dtic.mil/dtic/tr/fulltext/u2/1004913.pdf

Here is the actual draft for the Next Gen small arms....

https://www.fbo.gov/index.php?s=oppo...=core&_cview=1
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Old October 24, 2018, 08:00 PM   #147
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Keep up the discussion. I am sure a 5.56mm wonder bullet is in the works or already on the shelf....

The Army just isn't as smart as some of you guys or as knowledgeable.
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Old October 24, 2018, 08:29 PM   #148
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OMG. What an IDIOT

Proving that you can lead someone to knowledge, but you cant make em THINK
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Old October 24, 2018, 08:53 PM   #149
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OMG. What an IDIOT

Proving that you can lead someone to knowledge, but you cant make em THINK
So primary sources and first hand knowledge is idiocy to you?

Or do you mean I should think just like you?
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Old October 24, 2018, 10:35 PM   #150
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Doesn’t matter, whatever cartridge the Army settles on will still be hamstrung with a less effective bullet design.

So whatever the army comes up with, a civilian analog will out perform it. The military version will be used to shoot soda cans.

Will still need a lighter bullet at high velocity to get the job done.

Or we just issue everyone 30.06 and 8rd clips like the days of yore.

As far as this thread goes... time to stick a fork in it.
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