AusVarmint

This started as an attempt to in some way correlate the possible damage done by the kinetic energy of liquid displaced by a pellet in a water tub to that which occurs in a pest bird at about the same penetration depth.

Aside from inquisitiveness, it would be nice to have a simple test to compare various pellets at various velocities as to their probable effect.

Fairly crude but here it is:

The first stage was done some time ago and some readers may remember this result. A slip of 200 gm cardboard was inserted into a deep incision beside the breast bone of a pest Myna bird ( still hot ) and shot through with a Predator pellet. Left click to open for later comparison ( Graphic ) and to view the cardboard after removal:

http://img.photobucket.com/albums/v392/ ... Eexper.jpg" onclick="window.open(this.href);return false;
Note the lower cardboard was placed behind the bird. The exiting pellet then went through it and into raw sheep's fleece for retrieval.

Today and at a similar distance I set up The Great Aussie White Water Trough in abbreviated form. A frame with a sheet of 200 gm cardboard ( same as in the bird above ) was slotted in at approx the same distance as the bird test at a tad under an inch from the POI at the air-to-water interface :

Tank from pellet’s eye view as it would enter the small hole sealed on the inside with cling wrap.



Trough from the far end looking back at the frame and pellet entry window. Trough minus water and cardboard which slots into the frame:



The Trough was filled with water and two pellets were shot, a Predator poly tip .22 of 16 gr and a JSB 15.9 gr Exact .22 cal.

Of course the tank had to be re-filled, a new "target" slotted in and the window re-covered between shots… From the original water Trough tests of some years back I knew that a JSB Exact will travel 60 inches/ 5 feet horizontally through water from the Excalibre at a somewhat lower muzzle velocity than this test. As this tank was only 20 inches or so long, I placed a lead plate at the far end in the tank for the JSB Exact shot. ….. The tank was located at 22 yards and the mv was 1025 to 1030 fps for the two shots and at the POI velocity was about 910 fps and 33+ fpe for the Exact, a little less for the Predator pellet.

Result: The cardboard on the left is the Predator result; that in the middle is the JSB Exact result and on the far right of the third sheet is the hole stamped by the Exact into the sheet covering the lead plate at 18 inches horizontally from the pellet entry port.



The extent of the damage done by the displaced water pressure was approx 3 inches maximum diameter for the Predator and 2 inches maximum for the JSB Exact.





Note that the Exact still had sufficient energy to flatten its point on the lead sheet at the far end of the trough.



However though the Predator expansion diameters of the bird and water test Predators are same at 0.30+ inches, the expansion profile is quite different. Here is the pellet from the Myna bird shot seen with a normal Predator shot straight into wool fleece:



Discussion: Certainly the fluids from all sources and compartments within the first inch of the bird together with some other bits of tissue tore a significant hole in the sheet that was slotted in beside the breast plate.
There is however a bigger tear in the Predator sheet from this water tank test.
The Predator expanded to a frontal diameter of 0.31 or 7.89 mm in the water trough. As in all other water tests the Exact did not expand and retained its point on stability all the way to the lead plate. ( In earlier tests even at 5 feet of horizontal water travel the exacts always retained a point-first attitude with no semblance of tumbling ).

The expanding Predator did make the bigger area of damage encompassing an area of 7 square inches compared to say 3+ square inches for the JSB Exact.
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There would have been some other pellets tested, but it is amazing how much time can be spent on these things and the clean up was only managed just before the lady was due home from her meeting ! ……………..

Prior to the test I shot 5 Predators at 25 metres for group at this high velocity, 1025 fps from the JB OZ 1 BSA Hornet::



These pellets seem to be able to be pushed to very high velocity and not lose precision.

Kind regards, Yrrah.

Very interesting Harry. I was wondering if you have tried repeating the experiment with the red tip removed to see how much the tip initiates expansion. Glad you got cleared up in time.

Regards neil

stillair1 wrote:Very interesting Harry. I was wondering if you have tried repeating the experiment with the red tip removed to see how much the tip initiates expansion. Glad you got cleared up in time.

Regards neil

No Neil, I haven't but I doubt the red tip has much to do with expansion. I do believe that it assists in penetrating feather armour on birds though. I did an experiment once to see how much velocity was reduced by a simple set of Myna bird wings and it was surprising. .... Quote from an earlier report:

"Shot #1. Exact Over bare Chrony 897 fps. Shot # 2: Exact through pair of wings showed exit velocity of 855 fps, a loss of approx 42 fps ( lost V 4.68 % ); loss 2.59 fpe ( loss of 9.1 %); and 4.7 % loss of momentum...." end quote. ... I must repeat that with the Predators some time.

That red tip stays intact when the pellets are shot into wood and the Predators penetrated further in hard pine than did JSB Exacts.

http://img.photobucket.com/albums/v392/ ... edtoJS.jpg" onclick="window.open(this.href);return false;

It is an interesting pellet and one which everyone who shoots pests should try in .22 cal with high power FAC rifles that will deliver them to POI at 10 fpe or higher; the higher the better.

Kind regards........ Harry.

Very interesting Harry. I have been using the predators in .20 out of my R9, Lewis, as usual was very nice and sent me a tin to try. They are the heaviest pellet I have for the R9, I nailed 3 Mynah's in about 6 mins one morning with them, I had two fly about 10 meters and the third was a belly flopper. I had hit the first two just off of the center of there chest but they all showed damage where as exact shot mynah's can be very hard to find any holes in.

Very scientific...

Maybe you should look into "ballistics gel", that would be interesting. Large, cheap wax candles would also be nice to shoot into. I say this because they actually trap the pellet and don't let it sink down/go wild, the wax might simulate cartilage or medium tissue, the gel (duh!) being soft tissue.

It is interesting to see that the Predator pellet HP fold back on itself in the water trap test.

But I wonder if the action of the HP lead being folded back creates a larger displacement shock wave in the water as it hits the cardboard and that is why you see a larger tear for the predator... as the frontal surface area of the predator pellets becomes larger in diameter when folding back on itself compared to the JSB dome top.

Can I ask how does this test compare to hitting an Indian Minor?
I do not see 2in exit holes in my Starlings with a .20 cal with JSB's.

gigitt wrote:It is interesting to see that the Predator pellet HP fold back on itself in the water trap test.

But I wonder if the action of the HP lead being folded back creates a larger displacement shock wave in the water as it hits the cardboard and that is why you see a larger tear for the predator... as the frontal surface area of the predator pellets becomes larger in diameter when folding back on itself compared to the JSB dome top.

Can I ask how does this test compare to hitting an Indian Minor?
I do not see 2in exit holes in my Starlings with a .20 cal with JSB's.

Yes, undoubtedly the expansion of the Predator pellet causes a higher "rate" of energy transfer at the plane of the cardboard. Pellet Kinetic energy transfer is pretty much at right angles to the pellet travel. What we are seeing is an indication of the extent of that at the plane of the cardboard. If we take the area of a circle, which encompasses the extremity of the torn section, that area would be indicative of the extent of the pressure wave at the instant the wave passed through the cardboard. In a Myna at approximately the same distance from POI we see this result:

http://img.photobucket.com/albums/v392/ ... Eexper.jpg" onclick="window.open(this.href);return false;

The water soaked cardboard was slotted into an incision in a freshly killed Myna beside the breast plate / sternum and through to the back. The pellet was shot through from one side to the other ( and so also through the cardboard ) shown in the top half of the pic. The hole blown through and the tears and various fluids and other bits indicate displacement. The bottom section of the pic shows another cardboard sheet that had been placed behind the bird. The hole in that sheet shows the pellet hole after the pellet had exited the bird with no body fluids to transmit the pressure " wave".

There are at least two segments or "cavities" made by a passing projectile. The "permanent cavity" is that which remains after the event albeit filled with blood, other tissue fluids, bits of damaged tissue etc. The "temporary cavity" reflects the extent to which the adjacent tissues may be displaced during the event but because of their elasticity they return to the boundaries of the "permanent cavity" and the bounds of the true anatomical/ structurally damaged area.

In the pics of the water test cardboard, we perhaps have a window into all this but at just one plane along the pellet's travel. At the centre of the damage there is a small area that could be indicative of the "permanent channel" in respect of the cardboard media. ( This could be bigger in the bird ). The extent of the splits in the cardboard could be indicative of the transient extent of the "temporary channel". The relatively brittle non elastic cardboard has torn and remained so. In a bird the elastic nature of the tissues would have allowed the temporary channel to close with seemingly little damage.

However, a lack of obvious structural/ anatomical damage belies what functional/ physiological disruption may have occurred (important nerve function as an example).

This brings us to your other query. When Mynas are centre mass shot on the ground with round nose Exacts they tend to fall flat and show signs of life for a few seconds, generally no more than 5 or so. They almost never move off the spot. When shot with the same high power and a Predator they fall flat and almost never show any signs of life.. total functional breakdown, which is what any pest controller or hunter wants to happen.

Now of course the end result is the same and one of the most often expressed cliches in discussion of relative merits of bullets or pellets is " Dead is dead OK" .. and so it is I guess.

The last point I may make is to refer to the obvious.
Degree of penetration is directly related to momentum, velocity x mass, whereas kinetic energy is velocity x velocity x mass. So we cannot avoid the conclusion that if a pellet dumps its KE fast, due to expansion, then it is also losing velocity fast and so momentum too suffers and so penetration is reduced and potential for an extended permanent wound channel is compromised. On the other hand if the pellet retains its KE well because it has not expanded its frontal area, then it retains its momentum too and can travel deeper where it may continue to do structural damage.

So it is horses for courses. ...

Thank you for your interest Gigitt... it is good to feel one is "talking" with others sometimes. On the 'net something may be read 100 times but only attracts maybe five responses or less. It is then hard to gauge if the topic was really of any interest to the readers ........ Kind regards, Harry.

fritz wrote:Very scientific...

Maybe you should look into "ballistics gel", that would be interesting. Large, cheap wax candles would also be nice to shoot into. I say this because they actually trap the pellet and don't let it sink down/go wild, the wax might simulate cartilage or medium tissue, the gel (duh!) being soft tissue.

Ballistic gelatin has its place but without high speed photography and digitization it is hard to quantify anything. you just get a fleeting glimpse.

Although there are glaring differences between water and living tissue, the body is after all 2/3 water and the vital chest zones on birds and animals have an even higher % of liquids, blood, lymph and water. Wax, putty and phone books are a lot further from living tissues by nature. A very well soaked ( say 1hour submerged ) phone book is pretty good as a medium and you can see the result afterwards ....... Kind regards, Harry.

stinkitup wrote:Very interesting Harry. I have been using the predators in .20 out of my R9, .

I must try them in my Sheridan .20 cal some time. ....... Kind regards, Harry.

stillair1 wrote:Very interesting Harry. I was wondering if you have tried repeating the experiment with the red tip removed to see how much the tip initiates expansion. Glad you got cleared up in time.

Regards neil

Neil today I tried the Predators in the test minus the tips. I will report on it in time as I spent the whole day testing a number of pellets. Guess what? The "Pointless Predators" expanded the most and just pipped the pointed Predators in the underwater paper tear result but only by a tad. I expected that. But those little points do the jobs intended for them viz., getting through feather shields and penetrating plate bone and smashing dense bone. You may have seen some of those experiments I did back a couple of years ago.

It will take some time to put a report on today's test together. There were some surprises ...... Kind regards, Harry.

PS. All my stuff could have been made available to the readers on that UK Forum ... but then they have Gary Cooper, Ben and Co., to entertain and "educate" them .. Right? .. I sometimes wonder just how many of the quiet achievers and good shots there have now duplicated the things I was doing back then and are nodding quietly to themselves. It is certainly happening in NZ, SA, USA, Russia, Netherlands and other places now. ... Kr, H.

Thanks for that info Harry, I reckon that most of the uk shooters will not see the full potential of that pellet as a majority are stuck at sub 12ftlb.
We seem to be living more and more in a big brother is watching state over here, and with the current gov trying to ban anything and a gutter press we'll be eating with spoons only in this nanny state Do gooders have recked this country.
.Don't worry Harry a few of us are pushing the boundaries quitely. I effectively pushed my limit another 19yds last year, under ideal conditions. for those loong rabbits.
Btw nobody believes me when I say my 24ftlb fac .177 with heavy prems is excellent on pigeon. With 12ftlb you always get some movement as they tumble, with mine they just fall of the perch without a twitch like a plastic decoy. I did not believe, at first, but repeatability showed there's something going on which you would not expect.

Regards neil

stillair1 wrote:Thanks for that info Harry, .......... some of us are pushing the boundaries quitely. I effectively pushed my limit another 19yds last year, under ideal conditions. for those loong rabbits.
Btw nobody believes me when I say my 24ftlb fac .177 with heavy prems is excellent on pigeon. With 12ftlb you always get some movement as they tumble, with mine they just fall of the perch without a twitch like a plastic decoy. I did not believe, at first, but repeatability showed there's something going on which you would not expect.

Regards neil

Neil, there is a common myth that a pellet must stop in the quarry and not "pass - through" in order to be most lethal. .. Well Hello!! .......
It is the pellet that does the most work in the shortest time in the quarry that is the most lethal, presuming hits in the same place.
The work done is equal to the KE delivered... momentum/ penetration also plays its part
A higher velocity "pass through" may do more work in less time than a lower velocity non pass- through.
At a given POI V the pellet that expands may do more work and stay in than a similar pellet at the same POI v that doesn't expand but passes through.
An expanding pellet that delivers all its KE before reaching a vital depth may be less lethal than one which does less work but does it at a more vital depth due to better momentum...

We could go on..... The "rate" of delivery too is important which is where the "power" thing enters the scene as power is the rate of doing work. The higher the time -rate of work done ( KE transfer ) the more lethal. .... Well OK .. "dead is dead" but then there is the time- to- die part of the equation too. Fast is better ??

The "pass-through / non pass-through" thing is far from a simplistic black and white concept.

Your pass-throughs on the pigeons are obviously doing more total work in the birds ( and at higher "power" ) than a < 12 fpe gun can deliver with the pellets in question whether the latter "passes-through" or doesn't.
Kind regards, Harry.