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Air Gun Home Forum Index » Pellets/Ammo » High Velocity Pellets lose accuracy Goto page Previous  1, 2, 3, 4  Next
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PostPosted: Sun Jul 26, 2009 9:12 am Reply with quote
Capt. Slappy
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pellets are like a pickup with a cap on it.... - the tailgate and the caps door.
how much fuel does it take to push that truck 200 miles?
yes weight does play a factor
but that big open end is an anchor to yer projectile

Pellets are not made to go sonic period.

and on tumble which kind ? in flight or after target hit
the 5.56 did after the hit not in flight
if you have an hour glass print ... thats in flight and considered a fly away
the 5.56 used an alloy wire on one side of the lead before being swaged.
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PostPosted: Sun Jul 26, 2009 9:56 am Reply with quote
fritz
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Reading some of the back posts about vacuum pressure on the tail... is that why boat tail bullets have a higher BC than others?

I may have said this before, but if the pellet/bullet is spinning fast enough nothing should really cause it to tumble because that force would have to be greater than the centripetal force.

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PostPosted: Mon Jul 27, 2009 1:32 am Reply with quote
Mark5043
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I use my 50 ct. package of Raptors,that came with my Gamo Whisper .22 as a paper weight."They sure are purdy to look at,being gold plated and all". Jerk It 'Tard Gay Rolling Eyes

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PostPosted: Mon Jul 27, 2009 2:28 am Reply with quote
kanyon
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Its all 2 do with CG & point of highest pressure...

when the point of pressure is in front of the CG
the , pellet , arrow , spear , aeroplane ,rocket etc
will tumble..

Pellets are designed to have more drag at the rear to stop this..
As the speed of the pellet increasses low pressure voids develop
along the sides then the tail no longer has any air pressure / drag
so the centre of pressure is at the front then the front wants to become
the back...
The longer the pellet is the more stable it will be...and the higer speeds it will reach before it becomes unstable.....

Pete
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PostPosted: Mon Jul 27, 2009 8:30 pm Reply with quote
TONBON
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yes a boat tail greatly increases ballistics in a bullet.
what if "they" made a pellet w/ a boat tail. but also had, not just ribs, but a short skirt.
you would only need enough to get hit by the air as it comes.
but you could still get the benifit of the tail.
the next prob is weight. hollow might work. but some lightweight filler might work better.
Question
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PostPosted: Tue Jul 28, 2009 9:56 am Reply with quote
fritz
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Take a standard pellet and turn the skirt down on it. Then it should have a more "boat tail" to it, and still have a skirt.

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"I never set out to be wierd, it was always everyone else who called me it" -Frank Zappa

Speed is impressive, accuracy is deadly.

It's not that I'm not a people person, it's just that I'm not a stupid people person.
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PostPosted: Tue Jul 28, 2009 7:52 pm Reply with quote
TONBON
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you would need a full width skirt to catch the air.
an idea might be to glue a predator tip to the rear Idea
full skirt w/ the tail. i think a pred tip is not quite big enough.
but the idea should work Evil Plot Evil Plot
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PostPosted: Tue Jul 28, 2009 9:14 pm Reply with quote
Slavia
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Quote:
an idea might be to glue a predator tip to the rear


It would have to stick out pretty far to the rear to catch the airflow - kind of like a bottle rocket:


Here's where the original photo came from - a pretty good article on this same topic:
http://www.airgun.co.uk/Airgun_Accurracy.html

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PostPosted: Wed Jul 29, 2009 7:58 pm Reply with quote
TONBON
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YEA, it would need to be much bigger to get the desired affect.
is that pic to scale? did you add the tip to the rear in the photo?
i was thinking along the lines of a burner bullet shape w/ a rib or 2 and a skirt about 2/3 the way back. past the max dia, back to about where the dia really starts to shrink.
i guess i'll need to draw it out.
but it would be very heavy. it would need to be either hollow or have a lighter center.
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PostPosted: Thu Jul 30, 2009 7:37 am Reply with quote
Slavia
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Quote:
is that pic to scale?


Roughly - I found a picture of a predator and expanded it to match the diameter of the pellet shown.

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PostPosted: Thu Jul 30, 2009 11:41 am Reply with quote
Capt. Slappy
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Warning : If you start designing anything like above ...
Make sure to take precautions and realize you are most likely to have a flyaway pellet.

Also make sure not to have any form of muzzle brake on yer air gun.
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PostPosted: Thu Jul 30, 2009 8:39 pm Reply with quote
TONBON
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I WAS THINKIN' ALONG THE LINES OF..
sry cps, My fabu paint skills.
it would be long and heavy. i guess a solid might work in a pcp.
it would realy need to be lightened up.
maybe good w/ some pba material, Question

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PostPosted: Thu Jul 30, 2009 9:38 pm Reply with quote
fritz
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Is the skirt really necessary? Has anyone tried full size pellets without a skirt? They would have to be longer than the ID of the bore to be stable I guess...

I think that the skirt may not have that much effect. Is the bore on anyone's .20 rifle big enough to fit a .204 bullet? Or has anyone tried a .17HMR projectile? Those two varmint bullets are light enough that a high powered airgun could easily fire them at effective velocities.

If we eliminated the skirt from our pellets, then we could possibly increase the potential range of airguns by some distance. I do see the repercussions of these high BC pullets (pellet bullet Cool ). The pullet could potentially be lethal at much further ranges- which can be a bad thing. But wouldn't a pullet be great for something like a condor? - Increase barrel twist rate to maybe 1:12 and with a .22 pullet in the 30gr range, with a BC of maybe .075 (double a 32gr EJ?). WOW. I could see that being devastating.

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"I never set out to be wierd, it was always everyone else who called me it" -Frank Zappa

Speed is impressive, accuracy is deadly.

It's not that I'm not a people person, it's just that I'm not a stupid people person.
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PostPosted: Sun Aug 15, 2010 8:23 pm Reply with quote
xanderman
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2RCHA wrote:
getting back to the tumbling rnd,,you'll usually get that happening to your rnd(pellet)when there is too much force projecting it, and basically the projectile can't handle it, Wink , Andy.

Usually it is because the rifling is worn out, the barrel worn out or the design of the rifle is errant, ie, by sppecification there is too much space between the bore and bullet or a smooth bore. (or mismatched ammunition)
You can get a 7.62mm sabot 55gr approaching 5000fps with no tumbling, necked down .50/.375 over 5000fps no tumbling, but I've seen a 303 lee enfield at 3300fps tumbling with worn out barrel, 60 others from the same era all working fine with same ammunition.

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PostPosted: Sun Aug 15, 2010 8:28 pm Reply with quote
rsterne
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The longer the bullet for a given diameter.... the higher either the velocity or the twist rate has to be for the bullet to be gyroscopically stable.... ie it has to spin faster than a short bullet in the same caliber....

Bob

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High Velocity Pellets lose accuracy 
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