Projectile bad in short range but good for long?

[snipelango]

Hello! I was watching a video on YouTube, and the man said that there are pellets/slugs that perform poorly at close range but perform well at long range, and that they can stabilize with distance.
Is that possible?
Because if a pellet/slug doesn't group well at close range, it will be even worse at long range, since it's already destabilized up close, and this would only get worse with more distance, right?

 

[Scotchmo]

…
Because if a pellet/slug doesn't group well at close range, it will be even worse at long range, since it's already destabilized up close, and this would only get worse with more distance, right?

Not necessarily true. I have a slug gun that shoots 1.5moa groups at 100yds. That doesn’t mean that the projectile is destabilized. There’s often other reasons why an airgun can’t shoot 1moa. That same airgun shoots 1.5moa groups at 300yds as well.

I consider 1.5moa at 100yds just so-so.

I consider 1.5moa at 300yds to be good.

 

[3Crows]

I just consider eye of skunk at 30 yards, oh, well, maybe 50 if downwind, to be sufficient for my purposes.

 

[Ballisticboy]

Slugs and bullets are different to pellets and use different stabilization methods, so what goes for slugs does not necessarily apply for pellets. Bullets and slugs, if designed well, will damp out their yaw quickly i.e. go to sleep, and thus maintain a linear error growth with range. Thus, in terms of MOA, they will be the same at long range as they are at short. There will be some changes due to the increase in gyroscopic stability as the range increases, but again the growth in stability is much less for slugs and bullets than it is for pellets.

There can be problems with bullets as well, I have seen two bullets of the same design fired from the same gun where one quickly damped out its yaw and the other carried on with the same yaw magnitude. Dynamic stability on bullets and slugs appears to be very marginal.

If anything, pellets appear to be dynamically unstable, or at best neutrally stable, meaning that yaw will grow with range or stay the same. Couple this with the relatively large growth in gyroscopic stability, and group size growth is unlikely to be linear with range.

 

[Scotchmo]

Another possibility: A muzzle velocity spread that would otherwise cause an increasing vertical dispersion can sometimes be “tuned” out at a specific distance. Harmonic tuners are used for that purpose. So possible to have less vertical dispersion (more accurate) at a longer distance.

 

[caliusoptimus]

I read a story in a ballistics book recently... the short version is that a major ammo manufacturer was working on a lead free high velocity 22 round and there were problems. The round would group an inch at 50yds and 12 feet at 100yds. Turns out as the round was slowing down the center of mass became coincident with the center of pressure and it began to tumble. As it slowed down further it became stable again but pointing in an entirely different direction.

Anyway... I've heard of some fringe cases where a slug might be slightly more accurate at a longer distance. I don't know if it's a real thing that actually happens, or happens stongly enough to be noticeable. I wouldn't worry about it.

 

[Ballisticboy]

I read a story in a ballistics book recently... the short version is that a major ammo manufacturer was working on a lead free high velocity 22 round and there were problems. The round would group an inch at 50yds and 12 feet at 100yds. Turns out as the round was slowing down the center of mass became coincident with the center of pressure and it began to tumble. As it slowed down further it became stable again but pointing in an entirely different direction.

Anyway... I've heard of some fringe cases where a slug might be slightly more accurate at a longer distance. I don't know if it's a real thing that actually happens, or happens stongly enough to be noticeable. I wouldn't worry about it.

If the centre of pressure and the centre of gravity are in the same place, a spinning projectile becomes infinitely stable and therefore is most unlikely to tumble. Infinite gyro stability is used specifically for this purpose in vertical fire trials so that the projectile comes down backwards. In a normal trajectory infinite stability will mean the projectile will not follow the curve of the trajectory which will give increasing yaw but not tumbling. The yaw could produce Magnus forces which will give a large dispersion at the target. I have seen this happen with large calibre shells which landed 2 km to the left of where they were supposed to land in a farmer's field. He was not happy.

 

[Spartan]

Hello! I was watching a video on YouTube, and the man said that there are pellets/slugs that perform poorly at close range but perform well at long range, and that they can stabilize with distance.
Is that possible?
Because if a pellet/slug doesn't group well at close range, it will be even worse at long range, since it's already destabilized up close, and this would only get worse with more distance, right?

Yes, it's possible, but with a notable asterisk being that the close vs. long range performance must be relative to another projectile.

As an example, if a person is shooting a well-tuned gun with standard dome/diabolo pellets, they might see a 0.25" CTC group at 30yds. That result is sub-MOA. Very nice. But when they move out to 100yds, the groups open way up to 6.0" CTC, nearly 6 MOA, and what most would consider quite poor. So that scenario shot great at close range and poor at long range.

Now if we compare that to a higher BC projectile like a slug, you may see a 0.5" CTC group at 30yds. A little over 1 MOA, so decent, but not as good as the pellets. But then move the range out to 100yds, and the slugs may print 2.0" CTC groups. Quite a better better than the pellets at that range, largely due to the better BC.

So this was an example of where in a relative manner the slugs performed worse (relatively) at close range, but better at long range. The key is that it is relative to the other projectile, and this is why you will sometimes hear such comments that a projectile is better at long range than it is at short range. It's basically an incomplete comment, but can be true when taken in the full context.