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LSAT, cased telescoped ammo
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You are currently reading a thread in /k/ - Weapons

Thread replies: 102
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So apparently LSAT is getting pretty good now. For those who don't know, here's what they claim about its SAW variant:
- More accurate than M249
- Much lighter than M249, and not just the ammo
- Somehow sturdier and more reliable than the M249 despite the more complex mechanism and light weight
- The polymer casings don't conduct heat like brass does, meaning that the chamber doesn't heat up as easily, most of the heat gets ejected with the casing

They're making a 7.62 NATO equivalent polymer telescoped round now, and rumor has it a 6.5mm round of some sort (Arma 3, anyone?).
Also in case you're wondering, the caseless variant appears to have been abandoned.

So will this get anywhere, or will it be another eccentric US small arms program like many in the past?
The tech overall seems really damn cool, and if it works as advertised, it would be fantastic in the civillian market. I bet it'll sit in patent hell for a while though.
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>>28439224
that thing look like an up side down Kalashnikov
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>>28439224
>6.5 Grendel machine gun

my pee pee just stood up a bit
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>>28439224
>The tech overall seems really damn cool, and if it works as advertised, it would be fantastic in the civillian market.
will this thing work with magazine feed?
because the cartridge lack a neck, so i think they would have problem with mag feed gun
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>>28439328
Apparently it does, they did make this hideous monstrosity after all.
Afaik they're working on the MG before doing doing much with the rifle variant.

Oh, and I forgot the obligatory corny Textron video:
https://www.youtube.com/watch?v=uUUi7MJXycw
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I want to see an assault rifle version of this, in a bullpup and standard configuration.
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>>28439360
THIS hideous monstrosity.
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it look like a 5.56 version Origin 12
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>>28439377
Oh god, that looks like a bitch to take down...
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>>28439377
If you took the stock and foreguard off that'd be a fucking Bolter
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>>28439430
I just wonder how the hell it works; look at where the ejection port is. The barrel is also really high up. I'm guessing that it has the rotating chamber thing going on like the LMG, but how the hell does it feed rounds into the chamber?
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>>28439514
>but how the hell does it feed rounds into the chamber?
must be same as the animation in this video >>28439360
the mag would look like one of those 12 gauge mag
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>>28439514
>>28439584
I believe the rifle has a rising chamber rather than a swinging one like the LMG. Both use a push-rod to feed rounds from the magazine/belt through the push-through chamber. There's no headspacing or extraction functions to the CL cartridge or CT case, it's all controlled by the chamber and feed push-rod.

>>28439366
Because of the configuration, the rifle is already a pseudo-bullpup with the action being above/behind the trigger because the barrel sits over the magazine instead of in front of it.
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>>28439224
It'll probably be the way to go with the next generation. From what I've heard the ceaseless version they're working on hasn't been abandoned but is instead on a longer timeframe and telescoping is seen as the interim solution.
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That mechanism looks like its capable of a stupid high fire rate
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>>28440563
looking at the video I can see why they are putting casless on the backburner.
It really does not add any other complex meachanics to push the spent casing out. The only real advantage is less litter and obviously weight
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>>28439250
Dammit. It can't be unseen.
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>>28439377
And yet i still want one.
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>>28440691
Polymer is much lighter than brass anyway, and probably cheaper than any caseless casing, so if it works it would already be a real improvement over actual weapon systems.
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>>28440822
I don't quite get what's so good about caseless when polymer has so many benefits already, and does things that caseless doesn't such as insulation.
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>>28440563
>>28440691
>>28440822
>>28441168
The polymer cased ammunition offers almost all of the advantages that caseless offers without any of the downsides. Caseless will probably be put off for longer until they start looking at flechettes again or some other type of significantly lighter bullets as it would make the difference between carrying 3x as much ammo as soldiers carry currently if you went with polymer cased with flechettes or 4x as much if you went with caseless and flechettes.
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>>28439377
10/10 would throw in dumpster
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>>28439468
I like the way you think
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>>28439224

I'm pretty sure the brass acts like a heatsink, not the other way around.
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>>28441523
The heat is generated inside the casing, it can't get to the chamber as easily when the casing is made out of something that doesn't conduct heat very well.
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>>28441523
>>28441569
The heat is insulated from chamber by the plastic case and is absorbed into the barrel and carried away by airflow as the chamber disengages from the barrel and rotates.

So the cases and barrel get hot, but the chamber stays cool. Hot barrels lose service life and accuracy, but they don't cause malfunctions or safety hazards until the point of utter failure. Hot chambers are the problem, and the reason for quick-change barrels in other machineguns where the chamber is an integral part of the barrel. Hot chambers cause mechanical stoppages and cookoffs.
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>>28441523
this, OP is a retard

>>28441569
Heat is generated inside the entire barrel

>it can't get to the chamber as easily when the casing is made out of something that doesn't conduct heat very well.
So heat wont transfer from the rest of the barrel to the chamber automagically? Just staph now
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>>28439377
Did they really have to go with the M16/4 fixed-front sight post
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Get rid of the SAW. Replace with M27 IAR.

>Beat area and ROF are more effective.
>1000% more reliable.
>Easy to manufacture replaceable parts.
>More ergonomical
>lighter

Easy peasy.
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>>28441836
>No capability for effective sustained fire
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>>28441873

Don't worry, high capacity drum / casket mags will be made reliable enough for military issue annnnnny day now.
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>>28441836
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>>28441890
You still have a closed bolt firearm without a quick change barrel system. All you're doing is destroying the gun faster. The M27 doesn't do anything that an M4A1 with a high profile barrel doesn't do already.
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>>28441720
>So heat wont transfer from the rest of the barrel to the chamber automagically?
The chamber is separate from the barrel.
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>>28441720
A metal casing soaks up the heat and quickly transfers it on to the chamber, a polymer case acts as an insulator instead. It keeps the heat in the casing after firing and also resists heat transfer from hot weapon components, so it also reduces the probability of cookoffs.
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>>28441720

did you not see how the action works?

The chamber is completely separate from the barrel. The only time the chamber actually touches the barrel is when it swings down to fire.

If it operates like an open bolt analogue, the default position for the chamber is in the loading position, out of contact with the barrel.
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>>28439224
>6.5

That would most likely be the .264 USA

http://www.thefirearmblog.com/blog/2015/07/26/potd-the-polymer-cased-264-usa/

>Grendel a shit
>6mm grendel is interesting
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>>28442034
>did you not see how the action works?
Considering that OP didnt post a pic of video of either, no. And considering jewgle doesnt return anything relevant it might help if you fags were to post something relevant rather than meme pics.
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>>28442068
>Linking to TFB
>Ever
No one cares about your daddies 1911 Alex
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>>28442201
See >>28439360
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>>28442283
ty anon
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>>28441932
the IAR concept is pretty close to the Soviet RPK and RPK-74
and they work just fine
then you need a light weigh 7.62x51 MG for SAW
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>>28442488
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>>28439377

Taurus. Is that you?
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>>28441897
Fucking lol
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>>28439377
Are those casket mags? They look pretty fat.
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>>28441932
"SHORT CONTROLLED BURSTS"
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>>28439250
thanks asshole, now that's all I see.
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>>28442488
Except the RPK has an anemic round and a ridiculously low, unusably low ROF and -still- manages to melt barrels and have cookoffs after any prolonged period of controlled bursts (or a single drum full retard).
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>>28444602
>or a single drum full retard
this one took a few drums, but no cook off
https://www.youtube.com/watch?v=EwSJiAwoMpY
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>>28444735
>VEPR
>7.62x39 one at that
In what way does that have ANY relation to an issued RPK other than a similar receiver? Vepr barrels are much thinner, dont have the sporter handguard, and a few other key differences in relation to cooling.
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>>28444932
>Vepr barrels are much thinner
yep, RPK have thick barrel profile
so it would last longer than a Verp
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>>28445130
Well yeah, was just trying to point out it was an apples to oranges comparison.
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>>28439250
Well, if you look at possibly the most effective modern SAW, the PKM, then it makes sense why they'd do the same as that and add on to it.
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>>28445325
Isn't the PKM larger than an LMG?
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>>28444602
>Low ROF being a con
>5.45=anemic
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>>28445434
>lighter bullet at a lower mv from a 16" barrel compared to 5.56 M855 from a 14.5" barrel
>somehow still manages to burn 12gr more powder
Yes, it is literally the most anemic military rifle round in existence. No, that doesnt mean it doesnt work, just that it could be better (namely, change the case geometry so it trows the same bullet at the same velocity from a lighter, thinner case with less powder)
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>>28445434
There is a sweet spot on ROF. That sweet spot is about 740-770rpm. The RPK is significantly below that, and that is bad. The m249 is significantly above that, and that is also bad.
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>>28444602
There is literally nothing to back up what you are saying.
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>>28445913
Ok vatnik whatever you say.

Fact 1: Almost everybody considers 5.56x45, regardless of load, to be anemic. 5.45x39 is slower with a lighter bullet, so it is more anemic. It also has a wider case and uses more powder because it was designed around feed and extraction reliability instead of efficiency, which means bulkier mags.

Fact 2: The RPK had a cyclic rate of 600rpm when new, which as the gun wore would lower. This is one of the reasons it was discontinued in 1978, it was way too low and some of the older ones were in the high 400s. The RPK74 has a cyclic rate of 650rpm when new, which lowers as it wears. This is still universally considered hella low (same cyclic rate as the BAR).

Fact 3: despite a thick barrel with modest handguard coverage to promote cooling, a ridiculously low mechanical ROF, and an even lower sustained ROF since its limited to either 40rd mags or 75rd drum mags, its lack of a field changeable barrel has led to runaway and ruined guns under sustained use. Even with judicious use of short bursts.

The only currently issued machinegun in the world (that I know about) with a lower cyclic rate is the Browning M2, with pre-safety models not using hydraulic buffers having a fixed ROF of 600rpm. Newer models and anything with a hydraulic buffer are adjustable from 450 to 1200rpm.
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>>28446203
>Almost everybody considers 5.56x45, regardless of load, to be anemic
Really?
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>>28446327
yeah. are you going somewhere with this or just a no u wrong
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>>28446203
>>28446327
Does this look anemic to you? Not arguing that 5.45 isn't shit in all the common military loadings (temporary cavity only affects some organs such as the liver, if it doesn't hit one of those organs it will make a hole slightly smaller than what a 9mm hollow point would leave when it's fully sideways), but fragmenting 5.56x45mm most certainly isn't. The common loadings available at the time of full power rifle ammunition in use in WWII would leave small wounds compared to modern 5.56x45mm.
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>>28442443
Go fuck yourself you ignorant faggot.
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>>28446479
Pic related shows how some of the ammunition used in WWII performed, the .30-06 M2 ball performs similar to the 7.62x51mm M80 ball shown in pic related.
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>>28446514
and another pic.
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>>28446514
>>28446528
>I'm a huge faggot the post
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>>28446514
>>28446528
>have to go 70 years back to find results that favor him
hmmmm
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>>28446695
>>28446536
samefagging so hard
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>>28442068

so that's what Kiowa pilots when they get out of the Army huh?
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>>28439377
>improved ergonomics
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>>28445325
PKM is a GPMG
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>>28439224
bet it's gonna be a bitch to clean
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>>28446528

>the main area of effect is only 20cm wide

Compare that to the size of the average torso..

>inb4 m-muh hydrostatic shock
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>>28448091
you base that on what?
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>>28439224
>So will this get anywhere, or will it be another eccentric US small arms program like many in the past?
Judging by how other Nato nations now don't even bother doing anything similar like they did in the past when the US had these kinds of programs it seems they anticipate this will end the same way like the rest of them.
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>>28448327
A shame in this case, because this tech looks like it's not only a clear improvement, but also it seems to have matured enough to be worth it.
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>>28441569
>The heat is generated inside the casing
The by far largest contribution to heat buildup comes from the friction of shoving a piece of metal through a rifled tube of metal that fits so poorly it leaves marks.
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>>28448505
That causes the barrel to overheat. The chamber overheating is a different problem.
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>>28441948
>The chamber is separate from the barrel.
like a revolver? how do they prevent gas leaks?
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>>28448557
>how do they prevent gas leaks?
videogame magic
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>>28439224
>The polymer casings don't conduct heat like brass does, meaning that the chamber doesn't heat up as easily, most of the heat gets ejected with the casing
wait. If the poly casing doesn't take heat that well, then how does it carry away heat better when ejected?
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>>28448579
The heat is trapped within the casing and gets ejected with it, rather than being conducted into the weapon like with metal casings.
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>>28448613
that only applies to the chamber though

the hot gases and the friction of the bullet going through the barrel still produce heat
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>>28441897
wew lad thats the hungarian desert camo
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>>28448624
That's a given of course, the point is that the chamber is less prone to overheat so the weapon is inherently more cookoff resistant.
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>>28445885
>There is a sweet spot on ROF.
not that anon but: what does that even mean?
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So many fucking retards in this thread.
The polymer casing is not preventing heat from transferring into any of the moving parts, this isn't how the LSAT avoids unduly high temps in critical components.
If you would read the technical presentations on the project you would see that the action of the rotating chamber moves enough air through it while cycling to keep it relatively cool. This action was designed around the lack of a case heatsink, it is an integral part of the project.
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>>28448456
but not surprising after billions of dollars wasted in similar programs with literally zero to show for
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>>28448699
The other programs just used dressed up ARs with weird bullets. This actually looks new and innovative.
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>>28448568
so basically pic related happens inside the LSAT and it's supposed to be cooler?
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>>28448720
When I think of ACR or OICW or SPIW or whatever the fuck all those programs were called I don't think of dressed up ARs with weird bullets. I think of technological fantasies of procument guys who seek innovation by writing it into the requirements without any knowledge of mechanical engineering. And I think of billions of dollars wasted without any tangible results. Can't blame other Nato nations for not going along with the next iteration of this circus show.
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>>28448655
It mans that a too-low ROF is ineffective, because the time between bullets if youre suppressing or sweeping a target is so large things dont get hit.

And a too-high ROF needlessly makes the gun harder to control, burns through ammo, and creates a significant overheating problem.
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>>28448722
gas cools as it expands, friendo. just because it's visible doesn't make it hotter. also the LSAT doesn't have a chamber gap afair.
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>>28448633
Norwegian desert camo(irony, if there ever was), and a whole shitload of G3 mags, but close :p
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>>28448885
Both arguments seem purely theoretical to me. And not even very deeply theoretical. Just assumed common sense but bullshit in reality.
Human reaction time is shortest on acoustic stimuli and averages at about 0.15 seconds, i.e. to even start moving a muscle. This means even at 400 rpm one gets hit by the second round at the same time ones starts to move as reaction to the first round. Tests from WWII showed humans need a little over half a second to get fully under cover. So a 400 rpm weapon with perfect aim lands 4 hits. Quite sufficient, it seems.

But of course there is no such thing as perfect aim, which is why the upper bound is equally bullshit. The weapon and the ammo are at least one order of magnitude more accurate than the shooter. In combat the total error is completely dominated by the shooter error. This was confirmed in WWII and every subsequent war. Millions of combat reports had been evaluated. Thousands of injured and killed had been examined. Turns out the distribution of bullet hits is as random as those of fragmentation weapons like artillery and mortars.

In other words all those weeks and weeks of marksmanship training at the rifle range were and are completely pointless and an utter waste of time and money. Combat stress, physical exhaustion and extreme time pressure make aimed shots a statistically insignificant event in war. What matters is to get as many rounds off as possible in the short window of opportunity. This is why assault rifles were invented in the first place. And their introduction was fought by generals and leaders the same way as very high ROF machine guns are nowadays, with the same pseudoarguments that you use: ammo and overheating.
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>>28448885
Yet the best infanteristic performance in WWII had by far the Germans, i.e. the ones who embraced the high ROF concept to the fullest with the 1500 rpm MG42. And they were also the first to embrace the assault rifles even though technically the world could have had assault rifles even before WWI.

But generals said similar things like you: they said such a weapon would be great if you could kill an enemy many times over. But since you can't it just eats through ammo. They were completely unaware, like you, that a high ROF is necessary in combat for a high probability of hit per trigger squeeze. And that's what truly matters when stastically you need about 500 rounds per enemy kill. Full auto is for actually hitting something, not for suppression. It has been shown that single aimed shots every couple of seconds are perfectly fine for suppression. You do this when you don't see the enemy and only anticipate his position behind various covers. Everytime you actually see an enemy you should use full auto in order to hit. And the higher the ROF the higher the probability of hit.

We knew all this once. It's the reason we embarked on programs like SPIW or implemented a 3-round-burst option. We've unlearned this because we couldn't make it work over the decades that followed WWII, for whatever reasons: too challenging technically (caseless), ammo too expensive (flechettes), or gun looks too German (XM8).

The actual "sweet spot" of ROF is in reality: as high as you can get it without impeding reliability. Optimizing ROF for accuracy at the rifle range is a detriment to the effectiveness AND efficiency in actual combat.
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>>28448940
>gas cools as it expands, friendo.
no shit, sherlock. so it does in the barrel.

>just because it's visible doesn't make it hotter.
when gas is visible, i.e. emitting light, then, yes, it's hot.

>also the LSAT doesn't have a chamber gap afair.
meaning friction every time the chamber rotates back and forth at standard temperature? meaning more friction when the material expands at higher temperatures after a couple of rounds? meaning a gap when the material shrinks during arctic conditions before shooting?
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>>28448722
>>28449237
LSAT chamber to barrel is sealed by a deforming plastic endcap that holds the bullet telescoped in the cartridge. When the primer is detonated, the telescoping charge pushes the bullet into the rifling and the end cap seal into the gap. The seal is ejected with the case.

On the CL version, the chamber reciprocates slightly and has a sealing flange/lip built into the chamber and barrel mating surfaces.

Neither has any chamber gap or associated leaked gas or flame cutting during firing.
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>>28449317
Finally someone who seems to know more details. Can you give me a link to some further documentation?
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>>28449422
Ah, my recollection was a bit fuzzy, it's actually a much more clever two piece telescoped chamber that provides the sealing action.
http://www.dtic.mil/ndia/2009infantrysmallarms/wednesdaysessioniv8536.pdf
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>>28449470
Thanks a lot. The expanding chamber is for caseless according to the pdf. So it seems like a derivative of the expanding chamber that the G11 used, which makes sense as LSAT uses technology licensed from the G11. But what about the cased telescopic variant? In principle the same would suffice. But is it worth the added complexity and do they actually do it?
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