Slugs distance to “stabilize”?

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Centercut

Centercut

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I’ve heard this numerous times in the forum. Someone posts a 50 yard group with slugs, and then the 100 yard group, and the 100 yard group is as good as the 50 yard group. And invariably, someone chimes in that “slugs take time to stabilize” as the reason. 

I’m not sure what that really means, and if that’s actually true? So am I to believe that at 50 yards the slugs were wobbly and not stable, then at 100 yards they became stable? And somehow when they were unstable, they automatically corrected their unstable flight path to get back on the intended line of flight? So the ones that were unstable to the left corrected back to the right, and the ones unstable right corrected back to the left? How did they know which direction to go when they were off track to correct?

Maybe Bob Sterne at Hard Air Magazine will do an article on this to either confirm or debunk this theory...
 
So this phenomenon, which to be clear its existence is still contested, is called "epicyclic swerve." Brian Litz is one of the most accomplished ballisticians of our time, and wrote this article on this very subject. I hope you find it informative:
http://www.appliedballisticsllc.com/Articles/ABDOC104_EpiciclicSwerve.pdf

Beyond that, I've never seen an analysis of the subject which provides anything more substantive let alone conclusive. If anyone else has, I'd LOVE to read it. 



I hope that helps. :) 


*edit*
HA! Loren posted his reference while I typed mine. Funny enough we both used the same reference. :p 
 
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Thanks @loren and @sto ,Interesting article, but the author himself says that epicyclic swerve is not the cause of this possible phenomenon. 

His conclusions:

”The bottom line is that epicyclic swerve cannot cause smaller angular groups at longer ranges. The reason is because it’s so small. The main reason it’s small is because the bullet is precessing (coneing) too fast for the nose to steer the bullet very far off course. The nose of the bullet will usually trace out a complete circle in less than 10 yards for a dynamically stable bullet (one that will settle to zero coning motion after a disturbance, or ‘go to sleep’).”

And:

“Just to be clear about the conclusions of the modeling: The phenomenon of smaller angular groups at longer ranges was not disproven. The only thing I've shown is that if the phenomenon actually happens, epicyclic swerve is not the cause of it.”

He does state that it might actually happen, so it’s something that may occur, just no real proven reason for it. Pretty much inconclusive that it actually happens, and also that if it does, it’s not epicyclic swerve...

So two questions remain. Does it actually occur, and if it does, what is the reason?
 
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I'm with you there.

Don't think I buy this theory. If there is some sort of precession/wobbling that stabilizes at a certain distance, surely the near group targets should show slightly out of round holes? They never do though. Regardless that's the only form of stabilization I can reasonably see happening and shouldn't really widen groups.

I've seen some guys on YouTube and elsewhere talking about epicyclic swerve (and other forms of other stabilization voodoo they fail to name or explain) as what can only be described as some sort of automatic 'course correction', which I cannot see as physically possible. If the projectile starts off line, it stays off line. That article STO posted seems to agree with that.

I think that shooter error is a much bigger part of this than many believe. Even with pellets when shooting close I've noticed flyers/pulled shots often end up relatively further away from the group (in MOA terms) compared with shooting further out. I've think maybe people's expectations of shooting tiny groups close up adds tension to their shooting technique and magnifies their errors. At longer range you concentrate harder but also have somewhat tempered expectations and relax more. Probably part of why you can shoot a brilliant group at the beginning of a session and then try in vain to better it all day 😝
 
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Yeah this is why the phenomenon's very existence is controversial. Nobody has yet proposed a satisfactory mechanism. You'll note though even Litz perceives its existence. What you'll note though is a distinct absence of people going out and shooting ten groups of ten rounds each at 50 and then again at 100 yards and running a statistical analysis on mean deviation from center. *shrug* 
 
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Bryan has a standing offer for anyone... He will pay for an all inclusive trip to his facility if someone can prove the phenomenon to be true. If they get there and can not make the smaller groups at distance happen for Bryan to witness, they have to pay all of the expenses. To date, nobody has taken him up on his offer and succeeded to show smaller groups at distance...without external forces of course. I don’t think it happens, but who knows? It does go against simple physics as Marcos pointed out. Bryan’s offer and lack of people willing to accept the challenge goes a long way in showing that it doesn’t happen. 





Stoti
 
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Centercut, Marcos,how much would you pay if someone did make the sale? 😂 

In my humble opinion I believe it is true having seen seen it happening. 

The reason I believe the projectiles know what path of correction to take is that they are spinning on an axis( between the barrel and target) Or always attempting to ( programmed by the gun barrel twist rate power etc. ) . Correcting itself with every spin and spiral. At first like a top they wobble if the “propellor” spins it unevenly. But then it corrects itself! If the top is out out round it’ll wobble a little then too. 

And Marcos I have definitely considered what you said And made the necessary changes to eliminate human error but still the same thing. 

Better grouping out to 100 vs 30! With cast and swaged , store bought and homegrown. .22 and .25

That’s my two cents towards the answer.
 
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Good input everyone! All other things being equal, if you can’t shoot less than 1/2” at 50 yards you should never be able to shoot MOA at 100 yards. Unless the slugs exhibit some sort of homing sci fi Romulan Borg self correction mumbo jumbo. I’m not a believer in the smaller groups at longer distances. I’ve never witnessed it or had it happen to me.... And if it has happened, was it just a statistical anomaly? I.e., did it happen with one group or a series of five or more groups? And I don’t mean three shot (non) “groups”... ;)
 
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Are there not three physical forces working together to correct and stabilize? Propulsion, bullet spin , and the wind. The diabolo skirt creates stabilizing drag and the regular shaped bullets minimize drag . Both are using the wind to fly better( cut through the air ) by their shape . If something was put in place to stabilize something ( the bullet ) then stability is not inherent. The barrel does its part as the bullet travels through it, once the bullet is spinning on its own, if it is perfectly balanced and perfectly round it will spin perfectly through the air.! And we all lived happily ever after🤣😂🤣😂🤣😂🤣 lol

But when it’s not , after it leaves the barrel it’s up to the spin and wind. Projectiles being propelled with spin correct them selves as drillbits do , but are affected by imbalances. A wing causes lift and a round pointed or semi pointed projectile is going to self stabilize by the same means ( wind direction). Directing the air around itself evenly as it is being pushed forward. The wind helps and it hurts too. It pushes our projectiles When it’s windy, but it’s also necessary for anything to fly.

CC you asked and that’s my take on it .but I kinda think you had already made your mind made up already 🧐🤣😂🤣.


 
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I totally agree. You need the slugs to be stable as possible as they exit the barrel. Interestingly the AirHunter method of tuning for slugs also supports the notion that slugs won’t become more accurate as they travel between 50 to 100y. 

There method is to shoot at a short distance 25-30y and don’t bother going any further until the slugs make one hole at that distance. This is the opposite to the theory they will improve over distance! If you watch there videos they do really get great accuracy. 
 
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You know Michael, I hadn’t thought of that before but Air Hunters and Bob_O would both disagree with the increased accuracy as distance increases. For the same reason you mentioned about tuning at 30 yards before you move out further. Makes sense to me. 

For CB Daddy, my mind is never that made up that proof won’t change it... I’m not a flat earther... ;)
 
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Unless the slugs exhibit some sort of homing sci fi Romulan Borg self correction mumbo jumbo.
Click to expand...

You forgot the "Terminator" T2000 liquid metal principle! :p

I am old enough to have played with "Tops" when I was a kid. When the Top was thrown it might initially wobble till it reached an equilibrium of spin and got very smooth and vibration free. When I got older and started to play with gyroscopes I noticed a similar phenomenon Could it be Barrel Harmonics / shooter flinch causing an initial instability of the bullet spin as I witnessed with a hand thrown "Top"?
 
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I'm not stating that a projectile gets any more accurate as it travels, but when you see a quarterback throw a pass, many times they start out wobbling, yet end up being perfect spirals by the time a receiver catches it (although not ALL the time, depends on just how wobbly it starts out and the distance thrown). The trajectory remains pretty stable, yet it usually happens as the ball peaks and starts to travel downward that it is at it's most stable point.

I don't believe that there is any correction factor other than the projectile simply stabilizes with distance as it finds a balance point as T3PRanch pointed out. There are however footballs thrown that have a definite left or right hand tilt to them. Maybe that is the reasoning behind the 'magical homing sci fi Romulan Borg self correction mumbo jumbo'? 
 
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