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Air Gun Home Forum Index » Pellets/Ammo » High Velocity Pellets lose accuracy Goto page 1, 2, 3, 4  Next
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High Velocity Pellets lose accuracy 
PostPosted: Sun Jan 06, 2008 10:47 pm Reply with quote
Riptide
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Rolling Eyes Is anyone having accuracy problems with the new high velocity pellets? When their shot from an air rifle capable of achieving 1,100 fps or higher they lose their accuracy.
I have three air guns, two springer rifles and a Dana RWS (springer) pistol. The new HV pellets pattern will (but not great) out of the pistol and the lower velocity Daisy Winchester, but fly erratically out of my Gamo Shadow. I can achieve inch groups with the Gamo Shadow when shooting match wad cutters at 35 yards. But the group expands to six inches when shooting the Crosman Silver Eagle Hollow Point or Gamo Raptors. That kind of spread makes the HV pellets worthless when shot from a HV rifle.

Any comments or suggestions other than not shoot them from the Gamo Shadow?
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PostPosted: Mon Jan 07, 2008 1:40 am Reply with quote
Westonhill
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What makes a pellet accurate
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PostPosted: Mon Jan 07, 2008 2:23 am Reply with quote
AirGunEric
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I think part of the problem with the "high velocity" pellets is that they are designed to try and eke out greater velocities than a "standard" pellet shot from the same gun (i.e. same power)- not shoot better from a gun designed for higher output/velocities. As noted in the article Westonhill linked- anything around the sound barrier requires the entire design of a diabolo pellet to be ignored and a "bullet" used. Problem of course is that a gun that will shoot a 10gr diabolo at 1100fps will only shoot a much heavier 30gr lead bullet at 400fps- doing all sorts of funky things with its trajectory and range.

The problem here seems to be quite simple- manufacturers are just starting to go too far in the "numbers" game. The bigger the number, the more guns/pellets/whatever they will sell- so now we have "high velocity pellets" for lower-powered airguns and "high velocity airguns" that can't shoot projectiles that would be appropriate at those speeds. Maybe if someone designs a 10gr bullet, that would satisfy the requirement- but with lead that may not be possible- once you fill in the skirt and waist to make a proper bullet-shape, its weight is going to go up significantly.

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PostPosted: Fri Jan 18, 2008 8:02 am Reply with quote
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I think other than making guys w/ high powered springers stand in front of their chrony's with jaw's hangin', they were meant more for medium powered a/g's as opposed to the higher powered a/g's(even though the marketing ploys say otherwise)out past 10 meters PBA ammo tends to drift wildly. If you want to keep the velocity without sacrificing accuracy I suggest you try "Daisy" LeadFree Field Point's, they weigh in at practically the same weight(5.2gr.) and they seem to be alot more accurate I find, and you may want to try using "Skenco's" in either type 1@ 5.7gr., or type 3's @8.5gr. http://www.dlairgun.com/pellets.htm#skenco here's a place where I get mine from, as you can see, they also give you a 20% increase in velocity as well. Give them a try, I'm sure you'll be pleasently surprised, Andy.

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PostPosted: Fri Jan 18, 2008 8:57 am Reply with quote
The outdoorsman
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has it ever been proven that pellets "tumble" after they hit the sound berrier?
i don think that they do....
why dont bullets tumble then, some going mach 2

how can benjamin come out with a gun that will shoot 1250fps with normal pellets and 1500fps with leadfrees? they will never sell any because they wont be able to hit $h!t
something is missing here....

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PostPosted: Fri Jan 18, 2008 2:42 pm Reply with quote
23ib0d0n
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The outdoorsman wrote:
has it ever been proven that pellets "tumble" after they hit the sound berrier?
i don think that they do....
I've printed 'hourglasses' with a hot Diana 52 shooting supersonic. Keyhole cuts are a pretty good indication of
a} tumbling
or
b} something that defies all known laws of physics.
Make your choice.
The outdoorsman wrote:
why dont bullets tumble then, some going mach 2
When supersonic bullets slow to the transonic barrier, that DOES cause problems.
Extremely evident in the difference in the 100m group sizes between a super sonic .22lr round {cci stinger} and a .22lr match round {Lapua match}. At 50m group sizes are the same because the stinger is still supersonic at that distance.

The outdoorsman wrote:
how can benjamin come out with a gun that will shoot 1250fps with normal pellets and 1500fps with leadfrees? they will never sell any because they wont be able to hit $h!t
something is missing here....
Because BS sells, and anyone that knows better is going to use a pellet that is in the stable velocity range.
There are idiots out there shooting pigs with .177 guns so that the BS can sell a few more 'Magic pellets' with the so called 'super airgun' they've built.

Hype is used because BS sells, but not to us, that have more knowledge.

Knowledge is power.
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PostPosted: Fri Jan 18, 2008 3:25 pm Reply with quote
broommaster2000
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Which can also be translated as: A pig can be killed with a spiked club, or a hand made spear.

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PostPosted: Fri Jan 18, 2008 5:26 pm Reply with quote
The outdoorsman
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nice reply 23ib0d0n
something is still wrong there benjamin will not make a gun that will not have any accuracy....
think about it!

Quote:

When supersonic bullets slow to the transonic barrier, that DOES cause problems.
Extremely evident in the difference in the 100m group sizes between a super sonic .22lr round {cci stinger} and a .22lr match round {Lapua match}. At 50m group sizes are the same because the stinger is still supersonic at that distance.

this does not answer my question i am asking why that a bullet that is going over the sound barrier for example a .17 HMR 17gr moving @ 2550fps why does it not tumble?you decribed the opposite a supersonic bullet geting around the speed of sound either over or above

Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound aprox .8-1.2 mach speed...
i doint know the balistics on those cartridges but some .22LR bullest do not even go to the speed of sound

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PostPosted: Fri Jan 18, 2008 9:20 pm Reply with quote
2RCHA
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Hey there Shooter, Actually there were some types of ammo that was specifically developed to tumble one of them being the 5.56 mm AR15/M16 rnd. At the time NATO was using the 7.62 rnd which was, and still is a beast of a rnd that will go through pretty much anything you put in your sights, including your enemy, the 5.56 on the other hand, when it struck you would spin around your in-sides much like a blender, and that was caused by the way the round would be spinning(or should I say over-spinning) Wink .Cheer's,Andy.

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PostPosted: Fri Jan 18, 2008 9:35 pm Reply with quote
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It is coming down through the speed of sound that is the problem for bullets- they are losing velocity (i.e. energy) as they come down in speed- then they encounter turbulence crossing the 'barrier' and get more unstable.

When first shot, the bullet is still accelerating and has no significant power loss at that point so turbulence is negated, somewhat. It's coming down in velocity and through the sound barrier that causes the more significant issues.

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PostPosted: Fri Jan 18, 2008 9:36 pm Reply with quote
The outdoorsman
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2RCHA wrote:
Hey there Shooter, Actually there were some types of ammo that was specifically developed to tumble one of them being the 5.56 mm AR15/M16 rnd. At the time NATO was using the 7.62 rnd which was, and still is a beast of a rnd that will go through pretty much anything you put in your sights, including your enemy, the 5.56 on the other hand, when it struck you would spin around your in-sides much like a blender, and that was caused by the way the round would be spinning(or should I say over-spinning) Wink .Cheer's,Andy.



i heard something about that i think we may be talking about the same thing but
is this the gun that the germans (i think) made without rifling so that the bullet would tumble, and cause more damage because a mushrooming (hollow point) bullet is illegal?

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PostPosted: Fri Jan 18, 2008 11:18 pm Reply with quote
2RCHA
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I think the gun that you're thinking of is the STURMGEWEHR 44, which was the father of all all the assault rifles that we have today, it fired a 7.92mm rnd, and had terrific rate of fire, they say that if it came along 2 yrs earlier , it may have changed the outcome of the war, with Germany anyway's. There was quite alot of research & development being conducted by Germany prior to, and during the WWII, I even heard they had some wild thing's going on with air-powered gun's. Man, what I wouldn't give to see some of that technology, I can just imagine what went up in flames when the Allie's went marching through. LOL, Anyway's,amigo, 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.

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PostPosted: Sat Jan 19, 2008 8:45 am Reply with quote
Alstone
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The outdoorsman wrote:

Quote:

When supersonic bullets slow to the transonic barrier, that DOES cause problems.
Extremely evident in the difference in the 100m group sizes between a super sonic .22lr round {cci stinger} and a .22lr match round {Lapua match}. At 50m group sizes are the same because the stinger is still supersonic at that distance.

this does not answer my question i am asking why that a bullet that is going over the sound barrier for example a .17 HMR 17gr moving @ 2550fps why does it not tumble?you decribed the opposite a supersonic bullet geting around the speed of sound either over or above

Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound aprox .8-1.2 mach speed...
i doint know the balistics on those cartridges but some .22LR bullest do not even go to the speed of sound


The problem is that a subsonic pellet uses the skirt to stablise its self in flight, where as a supersonic pellet requires a diffrent design because at supersonic speeds the rear of the pellet is running in a vacuum.

It's like the early days of jet aircraft when they passed through the sound barrier they became unstable, this is now designed out and computers are used to control it. but a pellet is on its own.

Al

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PostPosted: Sun Mar 16, 2008 9:17 pm Reply with quote
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The 5.56 NATO tumbled from the first versions of the M16 because the original rate of twist (1:15"?) understabilized the bullet. The rate of twist was increased because the Air Force accuracy requirements were not met in cold weather testing. The current rate of twist (1:9" or 1:7") was adopted after the new heavy bullet (64gr vs the original 55gr) was incorporated to facilitate better long range accuracy and penetration. The diablo pellet was designed for subsonic use. Anything supersnic will need a 'true' bullet profile. The Super light pellets are BUNK! LEAD=DEAD!
Aloha Gang!

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PostPosted: Sun Mar 16, 2008 9:30 pm Reply with quote
2RCHA
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Actually clloydhi,One of the main reason's there was so much trouble with the M-16 in the early day's was the boy's at the U.S. Army corp of egineer's had a heck of alot of powder left over from the abruptly discontinued M-14, In their wise wisdom they decided to use the powder for the M-16 cartridge, which gummed up the internal's, and with the addition of the mis-conception of the "No Cleaning Required" standing order, I still have a service manual that was issued to the troop's with sexy girl's giving directions on "How to Do" from my brothers service day's in Vietnam Laughing, Cheer's, Andy.

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High Velocity Pellets lose accuracy 
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