Retained energy - .22 vs .177

[lensman57]

In the case of a live target what may also be considered is the lethal shock radius. I now a .22 does have a much larger radius but whether it is really that much more than a .177 at these sub 12 limits needs to be investigated.
I honsetly wish that the .22 had a none FAC limit of 17 ft.lbs. It would have made a lot of difference to the accuracy within the short air rifle ranges without being " particulary dangerous " as defined by law.

A.G

[krisko]

i agree, they should change it for both .177 and .22,


.177 wants to run around 900, that is clearly a fact by manufacturers now. That would yield 18fpe with 10grain pellet, for simplicity 18fpe for both .22 and .177.
.22 wants to run at around 30fpe in the US they all do that.

this is to keep up with advances in airgun technology. i would not mind to be registered or a small admin fee.
on one side the authorities say it is not humane to use airguns on the other side they dont allow you to use more power.

hunting pellets like polymag or barracuda extreme or the hollow point would expand better, enlarging the crossection. practically a .22 will expand to size of a .25 or more. a .177 will pop to a size of a .22

[Artfull-Bodger]

In the case of a live target what may also be considered is the lethal shock radius. I now a .22 does have a much larger radius but whether it is really that much more than a .177 at these sub 12 limits needs to be investigated.
I honsetly wish that the .22 had a none FAC limit of 17 ft.lbs. It would have made a lot of difference to the accuracy within the short air rifle ranges without being " particulary dangerous " as defined by law.

A.G

Your right on the money here, the problem IS the lack of energy, the inability to fire the projectile at a higher speed,

If for instance you fire a 10.3 gr pellet at 700fps into your test medium you will get particular sized hole (the shock radius, the distance the material is displaced) and it takes a percentage of it's energy with it as it penetrates through.

Now fire the same pellet at 900fps and you get a much larger hole yet the pellet takes even more of it's energy with it, it's the same pellet but the impact speed is the defining factor for the size of the cavity.

So because we cant use the 900fps, as it would be over 12ftlbs, all we can do is use a lighter pellet to create a greater shock radius or cavity whilst limiting the amount of energy wasted by over penetration.

But this simply does not matter unless you put your shot in the right place, and that's where the lighter faster pellet is more forgiving.

[krisko]

in the US they used to define lethal at around 60-80fpe. usually they count the number of boards the projectile can penetrate.

well we know superman
:-)

but there is more common sense there. you cant deny that..

[lensman57]

in the US they used to define lethal at around 60-80fpe. usually they count the number of boards the projectile can penetrate.

well we know superman
:-)

but there is more common sense there. you cant deny that..

Yes that was the old US Army test. I think it had to penetrate a 1/2" board of certain density at 30 or 50 yards, not so sure about the distance I am afraid.

A.G

[krisko]

regarding how safe it is: i dont see much difference between 12fpe and 30fpe, in the wrong hands or if you have a bad day, both are/can be dangerous.
The legislation sucks, just like the tasers, battons, pepper spray is outlawed in the UK, there are places where all these are perfectly legal as long as it for self defence ONLY. And the daily news are not really full of abuse not at all.

back to the topic:
have you seen graphs of ballistic coefficient as a function of pellet speed? There is a relationship, this has a maximum. There the pellets perform best in a specific barrel.
Typically it is over UK's legal limit. Basically all UK legal airguns are performing sub optimal. UK users are simply crippled!

i have no idea how to post an image here so here is the link
http://www.network54.com/Forum/58323...+with+Velocity

if we are talking .22 here are the speeds
18.1 optimum 800fps
15.9 optimum 725fps
14.3 optimum 650fps
13.43 optimum 615fps only this last one seems to be "optimized" for UK. the trouble is with this one:
if you set your gun up to shoot this like it wants to, you may go over the limit with heavier jsb heavy or monsters.

Seems retarded isn't it.

In the US people run them more like these:
13.4 gr. RS : 850 fps (~22 FPE)
14.3 gr. Express : 900 fps (~26 FPE)
15.8 gr. Exact : 950 fps (~32 FPE)
18.1 gr. Heavy : 1000 fps (~40 FPE)
not higher since the performance will also suffer if they exceed these numbers.

Right. so where are we then?

[GPConway]

i have no idea how to post an image here so here is the link
http://www.network54.com/Forum/58323...+with+Velocity

These results are typical of those assuming an unrealistic constant Cd (~ 0.204) drag law.
Back in 2010, the use of the Constant Cd drag law was commonplace. If the correct drag law is chosen (ballisticboy's drag law or Chairgun's GA which are basically the same thing) then the the BC v. Velocity curves will be close (within the bounds of experimental error) to being flat, horizontal lines. i.e., the BC value for each pellet is constant and independent of velocity.

Short version: you can safely ignore the linked thread and its conclusions in their entirety.

George

[krisko]

that is experimental data. not theoretical my friend

[TORNADOS7]

Yes that was the old US Army test. I think it had to penetrate a 1/2" board of certain density at 30 or 50 yards, not so sure about the distance I am afraid.

A.G

Sounds good to me, some 0.5" ply-woods would require some serious power to drive an airgun pellet through it... 👍

[lensman57]

Sounds good to me, some 0.5" ply-woods would require some serious power to drive an airgun pellet through it... ��

Well, they certainly considered the lowly .22 RF which is treated as a toy gun in the US as quite lethal at 50 yards. The air rifle is a different story. I have had the unpleasant task of answering back to a few US posters degrading our sub 12 guns on the NET but TBH and deep down they are not wrong. But that is how it is and we shall adapt.
I still think that the OP is probably best served with a decent heavy pellet in .177 as it has the speed advantage over a .22 pellet of the same BC. The JSB Heavy in .177 has near enough the same BC as a .22 16grs pellet but travels a lot flatter, gets to the target much quicker so there is less chance of the target moving off the kill zone and has a pretty decent energy transfer on impact.

A.G