The bullet is yawing heavy if not tumbling. It will keyhole a target.

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that's not what he said. yaw doesn't mean tumble. the bullets axis line is in a different angle(plane?) to the line of travel. think like a stretched out corkscrew that the point of the bullet follows and the tail is kicked out and follows later. it eventually settles. 6.5 Grendel been noted of this effect iirc.

ive probably used the wrong terms and explained it wrong, maybe someone who actually know wtf will chime in.

Yeah, that’s gonna keyhole something downrange

Never said that.

This is what you quoted, and said was dumb.
That is the quote I replied to, and posted a vid to show what happens prior to bullet stabilization
Read more post less.

My understanding as well, but that it will leave much more true with a good barrel. So either a shot out barrel, heavier grain projectile 5.45, or something isn't built right.

Russia doesn't care.

I'm now just in this thread to see who ends up looking like a dumb ass. With the replies that have been posted, there is no way for someone to not look like a dumb asshole at this point

WTF!!
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The AN-94 looks like an AK-74 and you operate it the same way, but it IS a completely different gun.



AK-74s don't have pulleys. That whacky thing is both piston and recoil operated.

Interesting...Doesn't happen here, or do only Russian calibers tumble when exiting the muzzle and eventually self stabilize? Must be a feature that enhances fragmentation.

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the thing is, ...

never mind.

pro-tip: spend less time in GD, and more time reading quality material.  
here is a start --> https://www.amazon.com/Modern-Exterior-Ballistics-Robert-McCoy/dp/0764338250

I believe the longer skinner bullets tend to do it more.
It has to do with the center of gravity of a round.
Ever seen a football start out kind of wobbly then go into a perfect spiral?

the term you are looking for is "epicyclic swerve".

any non-uniformity of gas pressure when the projectile egresses the barrel will impart an effect called epicyclic swerve. basically, a pressure imbalance at the crown "pushes" one side of the bullet slightly, which when combined with the projectile rotation (imparted by the rifling) causes a corkscrew motion during flight. this is much more common than you may realize. in fact, it is one reason a rifle may be more accurate at a distance than up close; the amplitude of the epicyclic swerve decays as the projectile is in flight. for some types of bullets, the result of the cyclic yaw "improving" at long distances is that the helix gets tighter -- counter-intuitively improving accuracy and precision at greater distances.

there are at least two components to minimizing epicyclic swerve: the quality of the muzzle crown and the uniformity of the bullet base. these two aspects define the gas interface just as the projectile exits the barrel.

the homogeneity of the gas interface just as the bullet leaves the barrel is CRITICAL to the accuracy of a single round and the precision of a group of rounds (consistency). homogeneity means the relief of the gas pressure at the muzzle should be EXACTLY equal in every direction. any distortion in this area pushes the base of the bullet slightly in one direction, leading to (and/or exacerbating) epicyclic swerve due to the slight aerodynamic lift in the initial direction the base was tilted. this is one reason that you don't stand a rifle on it's muzzle, as any damage to the crown results in the aforementioned pressure imbalance.

as for the projectile, the uniformity of the bullet base can be improved via OTM construction -- that is, drawing the copper jacket from the base up rather than the tip down. this results in a far more uniform base. the better you can control the final (parting) interface between the muzzle crown and the bullet base, the better the system accuracy well be.

incidentally, the lot to lot (aka fleet) variation of M855 is so high because the steel penetrator used in the SS109 projectile only needs to be off center by 0.001" and the accuracy of a given M855 round goes to shit thanks to epicyclic swerve the whole way to the target. and the next round fired will have different characteristics as well.

note that epicyclic swerve results in a very, very shallow yaw angle which dampens out in something on the order of 1000-2000 bullet diameters downrange.

epicyclic swerve WILL NOT result in keyholing at the target; keyholing is the result of dynamic instability of the projectile -- for example insufficient rotational velocity.

ps
everything you need to know is in
McCoy, R. L., "Modern External Ballistics, The Launch and Flight Dynamics of Symmetric Projectiles"

Nvm

That poor silencer they were testing with it.

Yawing a bit is not the same as tumbling. As it spins around its axis the tail of the bullet and the nose rotate around the long axis. With few more milliseconds of spin it settles down.

This is not the say the demonstrated firearm and ammo are not showing tumbling.

Well my OP clearly shows keyholeing, and if you watch the LAV video those bullets are standing straight vertical during travel.

You must keyhole in Russian.

I see you're newer than the 13'ers.

You're gonna need this.

No. not enough to get a side on hit like that.

Those bullets were hitting the muzzle device on the way out I believe. It looked from the video like the brake was moving somewhat independent of the barrel.

So Russian drunks still shank a few guns on their shift, who knew? Having some 5.56 AK's their shit accuracy is overstated. Shit ammo has more to do with it. Even my horribly canted wasr-3 is decently accurate, it just doesn't work great. My SLR-106FR on the other hand is awesome in every aspect. I wish I could have bought a Vepr-IV RPK or a cheap Beryl/Archer.

Edit: I'm no AK apologist either. I bought a unfired 106 CR that Arsenal absolutely refused to fix that was much shittier than the wasr-3. It was the most accurate of the three, but would FTEx over half the time. So fuck Aresenal and anyone who makes sub-standard guns. I enjoy all my non-ar rifles. AK's aren't magic or horrible in my experience.

The effect is called Fleet Yaw, and is present in all spitzer rifle projectiles tested by the US government:

"Yaw is the angle the centerline of the bullet makes to its flight
path as the projectile travels down range (Figure 4). Although the
bullet spins on its axis as a result of the barrel’s rifling, that axis is
also wobbling slightly about the bullet’s flight path.
Yaw is not instability; it occurs naturally in all spin-stabilized
projectiles. However, bullet yaw is not constant and rifle bullets
display three regions of significantly different yaw (see Figure 5).
Close to the muzzle, the bullet’s yaw cycles rapidly, with large
changes of angle in very short distances (several degrees within
1-2 meters range). Eventually, the yaw dampens out and the
bullet travels at a more-or-less constant yaw angle for the majority
of its effective range. Then, as the bullet slows, it begins to yaw
at greater and greater angles, until it ultimately destabilizes."


http://www.dtic.mil/dtic/tr/fulltext/u2/a519801.pdf

How the testing was done:
https://docs.google.com/viewer?url=http://www.dtic.mil/dtic/tr/fulltext/u2/a458409.pdf

Fleet Yaw was the reason M855A1 was designed, as it greatly effected performance of the m855 projectile:


Typical AK74 accuracy with 5.45 7n6 surplus ammo was around 1.75-2.5 moa in tests I've seen. I'm not concerned.

That's not how physics works. It's keyholing, and will continue to do so at any distance.

You fucken dipthongs haven't heard of epididemal angular oscillation? The bullet launches and if it hits even a speck of dust or a fly wing or water droplet from rain it goes fucken nutty and flies sideways.  Its actually 5 times more deadly because the temporary cavity is larger in one direction and more bullet energy goes into the target.  Ballistic autists such as myself have figured out you load the projectile backwards and the natural bullet spin cancels out the spin imparted by the barrel.  But only if you want to sacrifice the trauma benefits in favor of accuracy.  

There's a thread of yours from some time ago where you're talking about the effects of POI shift from a non-FF barrel, and you're quoting a known SME and member here and everybody on the thread is shitting on you.

That one actually made me laugh, considering you were absolutely right, and if it was him saying it, they'd have shut the fuck up and praised him, considering what his job title is.

Just came here to post that the dude at the end of the video runs like a girl. That is all

I'm not a physics expert, but that doesn't make any sense.

You understand it about half way, the whole getting "more accurate as longer distances" thing doesn't happen, once the yawing stabilizes. The projectile continues on the path that it started while yawing.

Brian Litz has had a long standing challenge for anyone who can actually demonstrate what you are talking about happening. But nobody has been able to do so.

Stabilisation improves as a result of velocity dropping faster than the rpms, but "accuracy" does not

This is what they should have done. The AR stock on an AK is so fucking dumb.

Add a nice rail that can hold lights and optics, etc. And equip with a suppressor. They really need to invest more in developing a decent optic, made by them and perhaps specifically designed for the weapon.

The Russians finally copied the secret of the M16.

I must say i like it. the keyhole can be solved with bullet weight or twist- easy fix. but they are modernizing.

That's what I think it could be.
Can not tell from crappy picture.

Some people might benefit from reading the Army Research Lab's study entitled Small Caliber Projectile Impact Angle Determined from Close Proximity Radiographs.

Seriously?

Bullets do not flip, end over end and then magically stabilize. They may wobble, but the LAV video clearly shows a bullet flipping vertically end over end....that's not fleet yaw, that's tumbling.

The OP also  learly shows bullets keyholeing.

It bounces around inside your body and scrambles your insides up.

That thread was awesome.

But what's a JDAM arclight?

JDAMs are precision guided munitions.
ARCLIGHTs are B52 Mag Dumps.

 That's not how physics work.

Blyat!

I am sure that maths out..................

Must be them special Peyronie's boolitz.

Put them together for "fuck the fuck out of that fucking guy."

He said high yaw rate, nothing about tumbling.  Yaw rate describes the rate at which the projectile yaws (rotates in nose up/nose down) before stabilization.  This is a well known phenomenon.



ETA: Sorry @jon101st, meant to quote joglee or Greenhorn or any of the other retards that can't read.

Subjects of Glorious Mother Russian were able for the first time to see the internals of this radical new gun...

An AK-74 with a Free-floated handguard, and a top-cover mounted rear sight...

Sorry Ivan, its the same gun Kalashnikov designed 60+ years ago, in a smaller caliber, which they adopted almost 45 years ago, with some add-ons from Tapco and the Valmet.

Granted, the M4 is just an M16, which is an AR-15 in full auto, and isn't new either, but we don't pretend it is.

Yeah, that takes some really interesting physics to do that.  

Yep.  It's exactly the same, except it is completely different.

And yet.................

https://www.physicsforums.com/threads/bullet-behavior-during-flight.369401/

And yet the bullets in my OP were keyholeing the target

The bullet in LAVs video was tumbling end over end vertically. That is not fleet yaw or any other yaw.

Also did you see my post of the M4? No tumbling end over end, so is 5.56 immune to "yaw" or can we just admit those bullets are beyond the norm.

Even your link says bullets can fly in a helix type pattern, what the LAV video showed was the bullet flying straight, except it was flip flopping like a dolphin while flying straight, that's not a helix pattern. In a helix pattern the bullet should still be point in the right direction, just moving kind of circular down it's path of travel.

What were seeing in the videos is the bullet going ass end up, down, and back around. Tell me you see the difference.