Velocity--how much is too much?


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JohnKSa
October 26, 2013, 11:20 PM
Here's a video from Ted's Holdover showing the same airgun (HW100) shot at 3 different velocity levels to demonstrate how accuracy is affected.

http://www.youtube.com/watch?v=QFou_4VqLBY

The difference is eye-opening. Power is great, but not if you can't hit what you're aiming at.

So why do manufacturers make airguns in .177 that shoot well over 1000fps?
The videographer addresses that question--it's primarily because that's what consumers THINK they want.

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RussB
October 27, 2013, 02:16 AM
As mentioned, velocity is a selling point, especially for entry level airguns that offer little else than a big "FPS" number. Many consumers are influenced by the FPS selling point. It's too bad

I have also found that most rated FPS numbers are grossly overstated, and after a few hundred rounds, they drop off even more due to oils being burned out of the chamber (which cause detonation and temporarily increase velocity) and poor quality springs losing some power. Often the factory velocity numbers are shot with uber-light pellets, with none offering accuracy or enough power to take small game.

Some shooter use heavier that normal pellets in their high velocity airguns to bring the accuracy back

Hawk 3/21
December 15, 2013, 04:15 PM
Hello,
I really enjoy ted's videos and applaud his tenacity in finding a solution. However there is a basic flaw in his statement that the manufacturer made the speed too high to stabilize the pellet.
Balance brings stability, speed is only a part of the equation. The error, if you accept that higher velocity can expand the range of uses for the rifle, is that the manufacturer did not properly match the rate of twist in the barrel.
Take for example the military's solution to improve the anemic 55gr 556 for combat use. The solution, up the bullet to 77gr. This slows & elongates the bullet. The new rifles being sold offer a 1 in 7 twist rate to accommodate it. If you shoot the 55gr in it, or the 77gr in the older rifles (1/11?), you lose accuracy.

While I applaud Ted, & wish I had access to his gun cabinet, I have nothing good to say about these companies that take hard earned money & sell unusable crap. Balancing bullet weight, velocity & twist isn't extravagance. It's the basics.

Why point this out...Ted's conclusion is correct.
If you base future decisions on an inaccurate premiss, your results may vary. I'm sure Ted is fully aware of this side of the equation, didn't mention it, but would still factor it into future decisions/purchases etc.

Personally I have always prefered heavy, slow thumpers over light weight speed, but to each their own.

JohnKSa
December 15, 2013, 11:02 PM
The error, if you accept that higher velocity can expand the range of uses for the rifle, is that the manufacturer did not properly match the rate of twist in the barrel.I think your point is accurate, but it doesn't change the practicality of the situation if you're using off-the-shelf airguns and conventional "diabolo-style" pellets.

Call it an issue with the pellets, blame the twist rate or focus on the velocity as the issue. All are correct, but we generally don't have control over any of those factors other than possibly velocity. So the bottom line doesn't change unless you have the capability to alter the twist rate of your barrel or make your own pellets...

On the other hand, velocity is often a parameter that the owner can vary to one extent or another--if by no other method than by purchasing an airgun in the velocity range that tends to work best. So while the issue is really over-spinning the pellets--a twist rate issue--it still makes sense to couch it in terms of velocity.

rcmodel
December 15, 2013, 11:20 PM
Take for example the military's solution to improve the anemic 55gr 556 for combat use.There was nothing anemic about the 55 grain bullet in the 1/12 twist M-16 used in Vietnam.

You were DRT, or at least missing a limb if you survived when you got shot with one.

The 5.56 NATO only became anemic after the rifling twist was changed to 1/7 and the 62 grain bullet became the standard. And after the barrel was shortened from 20" to 14.4" on the M4 carbine, which became the standard 'rifle' through default now.

It is simply too stable now, and won't tumble and blow up like the Vietnam era 55 grain load did out of the slower rifling twist.

rc

Mauser lover
December 16, 2013, 12:12 PM
I have simply ceased considering the velocity on the box. I always go online and check what weight pellet it was measured with. I am happy with 1000 FPS with an eight grain lead pellet. I am also happy with 1600 FPS with a 5-6 grain pellet (not lead), simply because I know that I can get it down to a reasonable level with a heavier pellet (like maybe a normal eight grain lead one). If everybody would use the same pellet weight (or pretty close) it would be much easier to figure out which one you actually wanted, but they will not be doing that anytime soon...

If you are having problems, it could be the twist rate, or any number of other things. In my experience you can usually remedy the problem by trying a different pellet. (I have no formulas for this, just trial and error, unfortunately)

RussB
December 16, 2013, 04:45 PM
Remember that a pellet's skirt must obturate (expand) and seal the air behind the pellet. Because of that, pellets must be VERY soft...and if you push a soft lead pellet too fast, you'll get barrel leading...and barrel leading significantly diminishes accuracy in an air rifle...and on and on it goes!


I've chrono'd a dozen or so air rifles over the years...none have reached the listed velocity, although the Beeman/Weihrauch guns I own come close. My observations show that the cheaper the air gun, the more bloated the velocity claims get.

The Straight Shooter's website used to list actual velocities with specific pellets...I don't know if they still do

http://www.straightshooters.com/

ChaoSS
December 17, 2013, 11:51 AM
So why do manufacturers make airguns in .177 that shoot well over 1000fps?
The videographer addresses that question--it's primarily because that's what consumers THINK they want.That may be why they advertise it that way, but not everyone is simply looking to punch holes in paper. Many people want the extra power because it will push a heavier pellet into the sweet zone of velocity. And that heavier pellet means more killing power when you shoot something.

JohnKSa
December 19, 2013, 01:33 AM
That may be why they advertise it that way, but not everyone is simply looking to punch holes in paper. Many people want the extra power because it will push a heavier pellet into the sweet zone of velocity. And that heavier pellet means more killing power when you shoot something.The videographer is a dedicated airgun hunter, so his point isn't at all about punching holes in paper. He simply did the video on the target range under controlled conditions to highlight the issue.

Airgun hunting is about precision accuracy. The targets are small, the killzones are smaller yet, and even a very powerful conventional airgun shooting conventional pellets is pretty anemic compared to a .22 rimfire. If you can't count on excellent accuracy, a little more velocity won't help you at all.

In reality, it's precisely when your concern is something other than punching holes in paper that very consistent accuracy, especially at long range becomes critical.

ChaoSS
December 19, 2013, 11:34 AM
The videographer is a dedicated airgun hunter, so his point isn't at all about punching holes in paper. He simply did the video on the target range under controlled conditions to highlight the issue.

Airgun hunting is about precision accuracy. The targets are small, the killzones are smaller yet, and even a very powerful conventional airgun shooting conventional pellets is pretty anemic compared to a .22 rimfire. If you can't count on excellent accuracy, a little more velocity won't help you at all.

In reality, it's precisely when your concern is something other than punching holes in paper that very consistent accuracy, especially at long range becomes critical.
I'm not saying that accuracy isn't important, rather, what I'm saying, is that when you are hunting, total fpe is important too, depending on what you are hunting. If you can drive a 10 grain pellet (or even heavier) at 800 fps you are going to be able to hunt thicker skinned/boned animals than if you can only drive, say, a 7 grain pellet at 800 fps. So that gun that is advertised at 1600 fps may not be useful in so much as it can push an alloy pellet at crazy speeds, but rather that it can push that heavier pellet into the sweet spot for accuracy.

JohnKSa
December 20, 2013, 12:05 AM
...when you are hunting, total fpe is important too...It's not a total non-issue, by any means, but if you can't count on excellent accuracy, its value is severely decreased.

You'll never be able to compensate for poor accuracy with more energy when you're talking about typical/conventional airguns without restricting the range to the point that you can get back all the accuracy you're giving up.

An extra 100, 200, or 300fps is only helpful if it doesn't hurt your accuracy.So that gun that is advertised at 1600 fps may not be useful in so much as it can push an alloy pellet at crazy speeds, but rather that it can push that heavier pellet into the sweet spot for accuracy.Right, and you would use those heavier pellets if you were aware that there is a sweet spot for accuracy when it comes to velocity and that the sweet spot is typically below 900fps when dealing with conventional airguns using diabolo style pellets.

Said another way, you'd know to use the heavier pellet if you knew "how much is too much" when it comes to velocity.

RussB
December 20, 2013, 04:09 PM
Note that a "way too heavy for that particular spring powered airgun" pellet can also cause damage. If the pellet is so heavy as to let a lot of air pressure build up behind it, it can cause dieseling which affects both seals & springs. Just sayin' :)

JohnKSa
December 20, 2013, 09:08 PM
Correct. In fact, very light pellets can also be hard on the gun because they may not provide enough resistance to prevent the piston from slamming hard against the end of the chamber.

The gun depends on the cushioning effect of the compressed air to keep the piston from hitting the chamber end at full force and if the pellet moves too easily, that effect is lost.

In the same way that the design "expects" a certain minimum amount of resistance from air pressure as the piston nears the end of its travel, it also "expects" a maximum amount of resistance. A very heavy, or very tightly fitting pellet can create too much resistance which stresses the spring and can cause dieseling.

ZVP
December 21, 2013, 11:42 PM
he question of too muxh power affects the shooter more than the quarry! Most small gane can be taken with a 750-800 fps .177 caliber rifle. Spring recoil , weight of the Piston and heavy cocking effort all eventually wear dpwn a shooter after a long day.
If you prefer easier handling, eaxy to see target hits and like action hits, then buy the SAME rifle in ,22 cal. I have a pir of Diana's calibered like that and each has it's own specific traits fir specialised jobs.
U auggest having at least one pair of rifles in each .177 and .22 caliber!
You have to consider wht the gun is doing to you before you need to play the "Super Magnum" club. Don;t worry, you'll get there soon enough...
First find a easy cocking, adult sized rifle. One with a long barrel to assist in cocking effort. Plenty of power in that velocity range shooting meduim weight pellets.
First decide on your range of s[ecies, choose s rofle as suggested and pratice a LOT! LOT! LOT!
You are going to spend a lot of time on the recieving end of a longtime experience. Take care to make it a plesant one!
BPDave

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