/k/ - Weapons

So, there is this CBJ cartridge, how does it work, if it really does?

They do seem to push the very light 9mm(?) projectile like it would be a usual bullet, but very light for the caliber, so the velocity is built up really quickly, but then the bullet detaches from sabot and flies like a smaller caliber one, with a lot better sectional density. You launch the bullet like it would be a light big bore with bad SD, while it flies like a small bore one with good SD, but without extreme wear on the barrel and pressures, while going beyond what they could achieve.

Link: http://www.cbjtech.com/

What are aerodynamic properties of a flechette compared to just a long narrow bullet of G7 drag model?

>>601707

It works like this: https://en.wikipedia.org/wiki/Armour-piercing_fin-stabilized_discarding_sabot The barrel has a caliber of 6.5mm, but the projectile itself is 4mm, the sabot is there to make up for the difference.

>>601715

Was expecting this to be a good old-fashioned throwing spear. I wonder if it's possible to design a spear gun that functions as a viable heavy weapon in modern combat. Anyway, flechette rounds are bigly badass. They have a lot of potential, but nobody's really working on improving them. That's just a damn shame.

>>601707

Also, almost infinite barrel life comes as a bonus to all this sweetness. Why have they not been adopted, they have everything?

>>601722

With the further development of subcaliber ammunition, i'm sure flechettes will also have more attention, it depends on whether they are effective or not if they go into production afterwards.

so, not sure if this is weird or not. DNR land is under lockdown firearms-wise b/c of wildfire risk, so a friend and I went up to the local quarry, which was empty, and wandered around looking for brass.

What was surprised to find, was three rounds of unfired, non-dud 556, one dud unfired round (556 or .45 I forget) and … something else. I've since figured out some of it.

steel shell, rusted, forgotten for a while. No dent so just ejected, but a silver bullet, no corrosion. I've pulled the bullet, and can say it's much heavier than anything else I have. 180-200gr or so, and definitely .308. Powder is long sticks, only 2/3rds filled so it "shook" noisily before I pulled it.

Shell is of same proportions as .308 winchester, but the head is tiny to make room for this huge primer; much bigger than large-rifle, which I have since I used to reload that caliber. As I don't have the dies now I can't try to pop the primer, see if it's box or berdan.

.308 steel with … nickel? FP 200gr bullet. I thought it was weird.

>>601756

Tungsten or depleted uranium are also used for heavy bullets, so it might have been one of them.

>>601756

> FP 200gr

Uh, flat base, spire point. Not a ballistic tip, not a round nose. No copper but fully jacketed – or solid nickel I dunno.

Also, bump, I guess. Can I get those flechette rounds for my .357? They'd look about the same, just be bigger.

Is sectional density really a measure of the lethality of a round? Articles i read say >.270 is for big game. This tungsten 4mm round has sectional density of .270, does this really mean this thing can put down an elk?

>>601764

SD is only important in penetration concerns in hunting. Longer bullets tend to punch deeper, some of this does come from weight and momentum affecting penetration through certain mediums like living tissue. It has little to do with lethality outside of making sure the bullet punches deep enough to hit something vital, which is important in its own right.

Elk? Flachette? No. Clean kills prefer "hydrostatic shock" permanent stretch cavities that do massive damage to internal organs for fast bleedouts, something a flachette cannot do. It does EXTREMELY poor damage. If you fire a round that does not cause "hydrostatic shock" you would prefer a very, very large bullet made out of soft lead or is jacketed soft lead with a flatter bullet face that will punch deep and crush a lot of tissue. Again, the tiny sharp flachette sucks, as its sharp shape decreases resistance and damage, and its tiny size means will probably poke little holes that won't kill cleanly or ethically.

Accelerator bullets have been tried on the civilian hunting market (5.56mm bullets in 30-06 and 308) that were so damned successful they discontinued them for lack of demand because of performance. The whole concept had its idea in super light projectiles and reducing recoil in order to increase hit probability, part of the reason why it sank and will never ever return is because it is a poor terminal performer.

>>601767

>Flachette

It's not one, just a longer bullet going at 3k fps

>Clean kills prefer "hydrostatic shock" permanent stretch cavities that do massive damage to internal organs for fast bleedouts

Clean kills prefer pressure spike that disrupts thin brain blood vessels or at least leads to quick decrease of blood pressure, resulting in brain going off, both only possible if you hit areas with a lot of blood vessels, i.e. lungs. Death from bleeding is not that "clean". Even with a heart shot, a human still can have ~5 seconds of acting, which is more than enough to dump a few rounds into you.

>the tiny sharp flachette sucks, as its sharp shape decreases resistance

This particular non-flechette has some feature that causes tumbling, though i'm not sure if it is necessary, as i do not really know how is temporary cavity created inside tissue.

>its tiny size means will probably poke little holes that won't kill cleanly or ethically

140 grain 6.5mm is considered comparable performer to 45-70 400 grain. Not much more difference than 4.5 and 5.56. Source https://www.chuckhawks.com/sd.htm

>5.56mm bullets in 30-06 and 308

556 have very low BC and lose velocity very quickly, though i'd be interested in reading about these attempts

>super light projectiles

only for caliber including sabot. Without sabot, the projectiles are actually very heavy for their caliber, hence high SD and good penetration.

>poor terminal performer

Isn't it the problem with the bullet construction, and not the round? Tumbling, soft points, fragmenting - there are many ways to make the bullet transfer its energy. 5.56 is also a poor terminal performer if it does not fragment, which it does not really do that often nowadays.

>>601764

like this anon said >>601767

I'd only add that it depends on what you're shooting, and how far away. High SD bullets are more accurate because they're more aerodynamic, which means they travel faster at longer ranges because there's less resistance. This means that they stay in the air for a shorter period of time and therefore are subjected to the forces of "windage" for a shorter period of time, meaning they don't stray from the target as much. They drop a little more but drop isn't a problem in long range shooting, windage is. This all becomes important at extreme ranges, like >500 yards.

It also depends on the caliber. If you really are going to go Elk hunting, I'd say a 180 grain sp 300 win mag should be your absolute minimum. I'd prefer .338 win mag or especially a hot .35 whelen 250 grain for large game.

>>601839

Also, you might not want a really heavy projectile:

https://www.thefirearmblog.com/blog/2016/08/21/modern-intermediate-full-power-calibers-019-russian-6x49mm-unified/

http://archive.is/rJYXY

>The 6x49mm Unified was not your average full-power military round. It’s a 6mm, or .243 caliber round – considerably smaller than almost every other round in its class. It fired a light bullet, just five grams (77gr), and had an incredibly high muzzle velocity of close to 1,150 m/s – that’s over 3,700 ft/s to the yanks reading this. These figures are much more characteristic of intermediate small-caliber, high-velocity rifle rounds, but the 6x49mm was no intermediate cartridge, as it produced muzzle energies of close to 3,200 J. Because of its high velocity, though, it was incredibly flat-shooting, and reportedly accurate to 1,500m. This claim seems extreme, but consider that the 6x49mm Unified boasts a supersonic range of 1,150m, a full 50% longer than normal .30 caliber full-power rounds!

Now imagine what would happen if it fired a flechette of the same weight through a tapered bore.

>>601839

I've heard of a type of bullet floated as an alternative to flechettes that's shaped like an arrowhead. Supposedly it does away with all the problems that flechettes have. Anyone know anything about this?

>>601783

Can you address my points in >>601779 , please?

I like this guy's thinking and explainations, what do /k/ think of this?

http://abesguncave.com/general-purpose-combat-cartridge-revisited/

>>601839

Being able to make a cartridge using a steel alloy projectile and a polymer case seems like a pretty big advantage to me.

How would such a cartridge affect the performance of a rifle grenade?

>>601839

>point against flechettes

i'm actually not sure if long G7 BC is worse than a flechette

>People often forget that usings discarding sabots in small arms is a bad idea, because they can injure nearby friendlies.

They are nylon, and fly for 10-50m forward, unless you throw them at someone at point blank range, they are a minor annoyance, not much different than having a brake.

Also

>Later, the perfection of discarding sabot ammo, which is based on the same concept of using a larger caliber barrel to fire a smaller caliber projectile at high-speed, negated the need for the squeeze bore concept.

>have a 4mm flechette with a 7mm sabot and a tapered barrel that goes from 7mm to 5mm

Tapered bore projectiles seem to have a fin that is bent when they are going down the barrel. The fin is part of the projectile, so nylon is a bad decision. It would also bring more complicated issues like losing flechettes' primary advantage - sectional density, loss of reliability, and even more complicated barrels, and we already have them almost out of a normal gunsmith's reach.

>>601856

>Being able to make a cartridge using a steel alloy projectile and a polymer case seems like a pretty big advantage to me.

Indeed, you could make them from scrap metal and hydrocarbons, both of them are common enough nowadays to not count as strategic resources.

>How would such a cartridge affect the performance of a rifle grenade?

I'm not sure, but I do fear that it would be a problem. If you go with bullet traps, then you will need heavy ones; and a bullet-through type might shear off the sabot.

>>601861

>i'm actually not sure if long G7 BC is worse than a flechette

It might not be a problem if you are only interested in ballistics, but longer cartridges need longer, and therefore heavier, weapons. 30-06 was replaced by 7.62 NATO only because the later has the same performance while being 15mm shorter.

>They are nylon, and fly for 10-50m forward, unless you throw them at someone at point blank range, they are a minor annoyance, not much different than having a brake

See: >>601862 Even today they are more of a curiosity than a real solution for small arms.

>Later, the perfection of discarding sabot ammo, which is based on the same concept of using a larger caliber barrel to fire a smaller caliber projectile at high-speed, negated the need for the squeeze bore concept.

Yes, in tanks. The US Army experimented with discarding sabots in small arms, and even after decades of research they couldn't solve their problems. https://en.wikipedia.org/wiki/Special_Purpose_Individual_Weapon

>Tapered bore projectiles seem to have a fin that is bent when they are going down the barrel. The fin is part of the projectile, so nylon is a bad decision.

Polymer is used for the sabot in APFSDS, and one of the challenges in that kind of projectile is that the separation has to be predictable. I don't see how making sure that it doesn't separate is harder.

>losing flechettes' primary advantage - sectional density

It's just a polymer sleeve around the projectile. That is already used in Russian armour piercing 9mm pistol ammunition.

>loss of reliability

What loss of reliability are you speaking of?

>even more complicated barrels

The barrels wouldn't need rifling, and with electrochemical machining you can make them in a single step from a steel rod.

You probably can make 6.5cbj ow similar telescopic. The problem with that is it cycles rounds completely different from modern brass, so any of your guns will not accept these. Still ,weight reduction is a great plus, though that same cbj with aluminum cases weights almost nothing.

>>601868

>longer cartridges need longer, and therefore heavier, weapons

Yeah, but the problem is even bigger with flechettes.

>Even today they are more of a curiosity than a real solution for small arms.

Only in small arms. Still, some wildcats and cbj seem to change that. They might not be very precise, but they do sole the issue of reaching extreme velocities from short barrels, as well as allowing very good penetration.

>Yes, in tanks.

tanks have scaled up guns. If it worked for them, why wouldn't it work for us? You know, first were cannons, small arms came later with technological development.

>I don't see how making sure that it doesn't separate is harder.

>It's just a polymer sleeve around the projectile.

Then it's not a flechette. Flechette is a needle with fins, not a steel core nylon bullet. If you go with that, why not just use AP ammo? It would be more effective than try to throw nylon at the enemy.

>What loss of reliability are you speaking of?

i meant consistency, my bad. It's easier to make sabots separate than to make a saboted projectile fly properly.

>The barrels wouldn't need rifling

Are you willing to sacrifice spin stabilization? Do you really expect any adequate performance afterwards?

>>601878

>And as I said before, this problem is mostly gone if you used telescopic ammunition.

Why use flechetes anyway, then?

>And we are discussing projectiles for small arms, is that correct?

Yes, i'm just stating that big arms used to be in the same state of things. It's not like they are that different.

>Yet to this day there isn't a good automatic rifle that fires caseless ammunition.

Yet. Small arms are still scaled down big arms, in a way. When technology allows, we do the same things in small arms. Muzzle loading, paper cartridges, multiple barrels, automatic fire, different cycling mechanisms, etc.

>So if you paint a flechette black, then it stops being a flechette and turns into steel core paint bullet?

No. Flechette is a shape. External shape. If you enclose the shape with a layer of polymer in the shape of a bullet, then you know what? You just made a polymer bullet with a steel core. If the space is retained, than it would jsut be impractical, have bad ballistics, still cannot be shot as is, etc. All the same problems as with a usual flechette.

>Is that a flechette with copper coating, or an armour piercing bullet with a copper sabot?

If it has needle-like profile and fins on the back, then it's a flechette. If it lost its fins in the coating, then it's just a bullet, thin or thick. With the same rules that apply to all other bullets.

>Most modern tank guns are smoothbore, exactly because they are meant to fire flechettes.

Touche. Still, how do you achieve any effectiveness out of a small flechette?

>>601885

>If the shape* is retained, then*

>>601779

"pressure spikes" is an unproven theory, and even among those that speak of that theory there are those that say its more dependent upon what stage of the heart pump and blood pressure of the animal is when the impact is made, perhaps the whole thing is a contrived theory to explain certain phenomena in hunting. Some animals drop dead while others run from the same shots; "pressure spike" is a poor explanation of why some of these animals with their major organs turned to jelly can act for a few seconds and others don't.

In any case, these super small diameter projectiles are poor for this purpose even if pressure spikes are indeed real. Pressure spike theory is observed in the same rounds that cause massive internal bleeding from hydrostatic shock. Projectiles of poorer damage won't cause this supposed phenomena from happening, so its a moot case.

Massive permanent stretch cavities remain the most effective way of killing game animals, as well as stopping fighters. Not perfect? Still the best route towards incapacitation we have when central nervous system hits can't be guaranteed. Those who have shot game in the heart with a high powered rifle and watched that deer or other animal run before collapsing kinda have referred to it as "not knowing its dead", well understood and observed. Then again is this the animal making a conscious choice with its last remaining moments of blood, or is it an uncontrolled reflex not indicative of having enough blood and stability to THINK and ACT. That deer ran 20 yards before it collapsed, it didn't aim a rifle, it didn't shout commands, it didn't do algebra, it sprinted in a fear reaction that might not require much more than impulses driving the body before it gives out.

Small needle projectiles will either ice pick or tumble, ice picking does extremely poor damage and tumbling projectiles aren't that great. The long needles might stabilize the projectile and prevent it from tumbling; the lack of weight in the projectile might keep it from tumbling effectively because it does not have enough momentum to effectively tumble far through hard flesh. Low energy, low weight, they will refuse to tumble or won't do very well. It does not offer us much in theory.

The venerable 6.5mm Swede is a moose killer alright. But the thing to remember is that the Swede Mauser causes, again, hydrostaic shock with expanding bullets. Nobody would be hunting moose with non expanding 6.5mm bullets. The 6.5 does well on such heavy game because it both expands with velocity and energy as well as having extremely good SD to ALSO penetrate deep. Military ball 6.5 sucks shit compared to soft lead 45-70 Gubmit. They can both kill a lot of animals, but the 6.5 relies on high quality, purpose built, non military ammunition. The 45-70 Gubmit needs only a hunk of lead cast well enough to hit the target well. Comparable SD, but the ballistics both externally and terminally are night and day.

5.56 NATO showed that with accidentally fragmenting bullets you can make the round more capable, otherwise its a poor performer. How are you going to make these thin rods capable of hyper velocity other than making them with very hard materials to take the strain of velocity and force? I've heard of .17 and .224 caliber shooters who have claimed to blow up bullets from excess velocity in experiments. How will these small projectiles be able to perforate hard barriers without hard materials? By the end of the day you have an ice pick bullet, no matter how you look at it. A poor performer.

>>601890

> "pressure spike" is a poor explanation of why some of these animals with their major organs turned to jelly can act for a few seconds and others don't.

Isn't it exactly about disabling the brain? Didn't anyone ever check the brain for the effects of this and compare?

>In any case, these super small diameter projectiles are poor for this purpose even if pressure spikes are indeed real.

They are pretty long so tumbling can increase the surface area and their high speed can cause more temporary cavity. Big bore light for caliber pistol rounds are actually doing less damage, mostly poking holes.

>Massive permanent stretch cavities remain the most effective way of killing game animals, as well as stopping fighters.

Agree, the most reliable one, at least.

>Then again is this the animal making a conscious choice with its last remaining moments of blood, or is it an uncontrolled reflex not indicative of having enough blood and stability to THINK and ACT.

It might not be able to do this only if the brain was damaged, but not to the point of immediate collapse, just enough for the basic reflexes to trigger.

>Small needle projectiles

If we're talking about 6.5 SBJ, it's not a needle, just a long and heavy for the caliber, but pretty comparable to 6.5 grendel, i suppose. Good velocity and an expanding projectile might be a lot better than a handgun bullet, which is what they are required to do.

>The 6.5 does well on such heavy game because it both expands with velocity and energy as well as having extremely good SD to ALSO penetrate deep.

Well, the energy behind sbj might not be as great, but it fires from a 200-300mm barrel, fits into any 9mm handgun and weights even less. If it outperforms 5.56(range, damage; weight size and price granted) it would be a dream. I guess i need a chart for energy required per game size, the same way all those articles had about sectional density, as i was surprised to see its SD near large game.

>How are you going to make these thin rods capable of hyper velocity other than making them with very hard materials to take the strain of velocity and force?

I think not using lead would avoid most of the problems. Brass, copper, steel, tungsten, depleted uranium all might do. The main technical issue is how to transfer the energy of a bullet into the tissue effectively.

>5.56 NATO showed that with accidentally fragmenting bullets you can make the round more capable, otherwise its a poor performer.

What about 5.45x39? It does not fragment, but the hollow tip makes it tumble reliably. How does it perform?

>>601890

To be fair there is quite a difference between moose in Sweden and in North America.

>>601907

>Expect that it's not true.

<A flechette is a pointed steel projectile with a vaned tail for stable flight. The name comes from

It's right there.

>Actually, if pic related is an effective design, then you could manufacture it from cross-shaped drawn steel, as the polymer on the front would give it the required form.

I think it's not. The polymer extension might ruin projectile's aerodynamic properties. Even if the fins are open, they are blocked by the sabot.

>The same way you achieve any effectiveness out of a small bullet: you accelerate it to a high velocity.

I've heard that if it goes over 3k fps you start having problems with air friction or something.