Barrell twist questions...?

[Seanh]

Nitemare... go look at aB 101 on YouTube. There's a guy on there that does exactly what you're looking for air gun ballistics with video and he shows that Corkscrew effect in one video

[Taso1000]

Sean,

Are these the videos you are referring to?



If yes I agree, Matt Dubber made an awesome series with those educational videos!

Taso

[Taso1000]

This video by Ted is also a great explanation of pellet destabilization at long range that Mr. Sterne mentioned.



Thanks,

Taso

[n2omike]

Bullets need a higher twist rate than pellets.
Pellets can still benefit from high twist rates...  for shorter range shooting.

The higher the twist rate, the higher the rpm the projectile spins.
The higher the velocity the projectile is fired, the higher the rpm it spins.

The more of a 'waist' the pellet has, the more it acts like a pellet.  The less waist it has, the more it acts like a bullet.  Some of the ultra heavy pellets with very little waist need to be driven at HIGH velocity in order to have a high enough rpm to stabilize and be accurate.  They require a powerful gun to be effective.  Either that, or a higher twist rate.

In the video below, the narrator talks about pellets and twist rate.  He said that even though pellets are 'drag stabilized' like a Badminton Shuttlecock, they still need spin.  He said without spin, when they exit the barrel, they would yaw back and forth before the skirt's effect kicks in, sending them in different directions.  The air pressure as they exit the barrel tries to blow the skirt around sideways, and send it cattywonker.   Spin helps keep it stable as it exits the barrel.

As was said, the spin rpm doesn't slow down very quickly as the pellet travels downrange...  just velocity.  As the pellet slows, it's spin is way too fast for its velocity, and it starts to spiral. 

He said twist rates should be geared toward the intended range.  He said short range barrels need higher twist rates, and longer need slower. 

How I interpret things...  If you want to shoot a Max of 50-70 yards, pellets are fine.  If you want to shoot much further than that, build a gun that shoots bullets.    Of course, with enough effort and zero wind...  miracles can happen.  lol

VERY interesting video!

[triggertreat]

A very informative post Mike!

[Seanh]

Yes that's the guy that does the ballistics videos and the one above shows the spiraling effect at. ong-range

[BackStop]

Thanks for the videos guys.

At least NOW I have an excuse for my lack of accuracy at +50 yards.  Yeah, like that is the ONLY reason! 

[SAGERAT NITEMARE]

Here is about the point in a link where miss-understanding starts showing up...I WASN'T talking about about "corkscrewing" or precessing around a point...I have understood that for many years...and "wasp waist" bullets have been around since Herters was in vogue, a LONG time ago.  I used to believe the "Herter's Hype" and swear by them and shot a lot of them...and later when I learned a bit...swore at them...you can't believe what they did in flight and I blamed MY shooting abilities.

Yes...at Matt Dubber has produces several very informative and up to date vids...I have seen all of them, I think...The age of the video has really come into its own and some very good people are producing info on ALL subjects.  He has shown about pellets what has been known about bullets and what is required if you want to go beyond the 100 yd mark...or "long range" in pellet guns.

It still boils down to velocity, length and caliber...and a boat tail or not...nothing more than the physics of projectiles. 

But while his vids are very clear and productive they are representations and not actual "flight data".

Taso...You mis-interpreted what I meant by "ESTIMATED VIEW", but that doesn't matter, I'm fully aware what BC is...I have guns that shoot bullets with BC's from ≈.100 in 17 cal to ≈1.00 in 50 cal at velos from ≈500 fs to ≈5000 fs...and have been shooting something  for over 70 years but I DON'T consider myself a "total expert" by reason of time and experience although I have learned a bit here and there...much of it is applicable to both AG and PG.

I want to see a high speed video of the AIR FLOW AROUND A PROJECTILE/PELLET and statistical/engineering analysis as have been done with airplanes, boats, bullets, birds etc.

Back in the "olden days" AND even today...when the sun was at the right angle behind you you could/can see the flight of the bullet by the reflected sunlight on the base of the bullet...just like a tracer round.  At ranges over 100 yds or where you could see the reflection for longer than a split second, if it was steady then your bullet was flying strait and stabilized...if it scintillated or blinked it was yawing and it usually printed oblong holes in your target.

Also back then when I was buying seconds from Sierra Bullets, there would be voids what caused the bullets to dance around like drunken pigs...I've seen bullets start tumbling out around 50 yds, blow up, whistle and make weird noises and take chunks of paper out of the target.  I'm sure there are other "ancient" shooters out there that have seen the same.

I think it is kool that pellet gunners are starting to come around and start getting deep into this sports and start asking all those neat questions and have the video tools to see the results. 

There are a LOT of shooters but really only a few experimenters and it cost time and money to experiment.

Good Shooting and thanks for the vids.