GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Ribbonstone on September 26, 2018, 11:24:08 PM
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No relationship to reality...an old (past it's prime cooking date) sweet potato is just a sweet potato...not a rat, pest bird,or small squirrel.
But it was fun to shoot them befor tossing them in the trash, and maybe (for short range where BC doesn;t cont so much) it makes sense.
About 15 foot pounds (.22) at the distance of impact:
(http://i157.photobucket.com/albums/t50/ribbonstone/ae6c5ba1-91f3-451c-ad8f-6c520b9b5556.jpg) (http://s157.photobucket.com/user/ribbonstone/media/ae6c5ba1-91f3-451c-ad8f-6c520b9b5556.jpg.html)
Do have to assume that a larger exit hole in a small thickenss of test medfia does equte to more damage in a small sized target critter...but that seems reasonable to me.
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Looks like hollow points for critters.
So why doesn't JSB make any of their pellets with hollow points?
They don't want anybody using them on critters?
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I do tend to shoot spoiled food (yeah...it'snot jut my wife,pretty much "everyone"considers that weird).
Well...for yearws a co-worker's father had a large (trendy"grovery store, and he would save me things (spoiled things) to shoot. Like a full sized ham, freezer burned turkey, or 8-19 pound beef roast. Kind of stinky, but I learend about about pellet (and bullet) reaction.
Really soft stuff in the thickenss of a pest bird doesn't showany real difference (although faster does seem to equal more "splatter", just like it would with water).
Hollow points are kind of "iffy" in accuracy...can get lucky and have one shoot really well, but they are more picky about that than round nosed. Wad cutters are nearly always picky about speed...past some speed, they just seem to go spastic (the .22 JSB's have been really good about standing up to moderate (800's) speeds).
For those who follow the business/investment end of things...a question:
Is it just my immagination? A few years ago, would find PolyMAgs when I clicked on "show all JSB pellets" at PA. Did they spin-off a seperate division/incorperation (lets say like BSA and GAMO), did they subdivide the same corperation (Like Benjamin/Sheridan/Crosman), or is it actually a totally seperate origin?
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No relationship to reality...an old (past it's prime cooking date) sweet potato is just a sweet potato...not a rat, pest bird,or small squirrel.
But it was fun to shoot them befor tossing them in the trash, and maybe (for short range where BC doesn;t cont so much) it makes sense.
About 15 foot pounds (.22) at the distance of impact:
(http://i157.photobucket.com/albums/t50/ribbonstone/ae6c5ba1-91f3-451c-ad8f-6c520b9b5556.jpg) (http://s157.photobucket.com/user/ribbonstone/media/ae6c5ba1-91f3-451c-ad8f-6c520b9b5556.jpg.html)
Do have to assume that a larger exit hole in a small thickenss of test medfia does equte to more damage in a small sized target critter...but that seems reasonable to me.
That looks like good "science" to me :D A pellet gun's ability to shoot a good hollow point is a large part of me liking it or not. They don't all have to like the same hollow point, but they need to shoot at least some variation of it well for me use it for tree rats and pest birds. I'm a big believer in using HP pellets, if the accuracy is there ;)
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Actually did fine a couple that shot CrowMAgs well enough to use, had a couple that actually shot H-Points well, and more than a few that were acceptable with poly mags. But even the o9nes that do shoot them well pretty much get used for shorter range small pest shooting as I've my doubts about their penetration in larger critters. Typical tree squirrels aren;'t that thick, and are fair targets for the rifles that do digest HP's well.
Keep a stash of 5mm Poly MAgs, which one riflelikes at least out to 30-33 yards at nearly transonic muzzle velocity (much past that 100 foot limit, they go kind of spastic)...but inside of 30 yards(even with their BC, still going in the high 900's) they transform a pest bird (like a cowbird) into a "puff ball
That's the part of HP's I've not yet captured in "sweet potato ": the faster they impact, the more dramatic the rapid energy transf is going to be. MAy not agree,but everything I've done over the last 50 years has pointed to HP's being more suddenly destructive (rapid energy transfer) the faster they are going when they contact test media (or actualy "critter").
Will bring out the "bigger boys" that do shoot these three pellets to faster speed...and that there will be an unexpected buy of large amounts of sweet potato (never could stand those nasrty tubers...but my wife likes them).
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Actually did fine a couple that shot CrowMAgs well enough to use, had a couple that actually shot H-Points well, and more than a few that were acceptable with poly mags. But even the o9nes that do shoot them well pretty much get used for shorter range small pest shooting as I've my doubts about their penetration in larger critters. Typical tree squirrels aren;'t that thick, and are fair targets for the rifles that do digest HP's well.
Keep a stash of 5mm Poly MAgs, which one riflelikes at least out to 30-33 yards at nearly transonic velocity(much past that, they go kind of spastic)...but inside of 30 yards(at about 4 digit speeds) they transform a pest bird (like a cowbird) into a "puff ball".
But if at all possible,it a simple WC can shoot well over the distance at hand,most oftrn use them....too simple to screw up, are going to "slap-the-carp" out of whatever they hit.
I agree completely. Usually, the longest shot I take on the squirrels/pests is around 40 yards at my house. I have the PP700 slinging the Terminators at 900fps(.177), and it will will shoot half inch groups at 30 yards all day long with them. The Bullboss with the polygon barrel will keep the Barracuda Hunters at 1/2" at 50 yards with them moving around 925fps. That's faster than I prefer, but the polygon likes it fast..
Like you, I dump the HP for the larger critters and move on to the heavier .22s like the Barracuda Match, JSB Monsters.
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Cool....I'll get to use up some of the less-commonly-used pellets as Fall sets in(not as many small pests to shoot....more squirrels); to get to use up some of the WC/HP pellet stash.
It's hard to find 15-20 willing critters to stand (or sit) at moderate range wile they get plastered by various pellets at various speeds...but I can certainly find 15-20seet potato "stand ins" subjects.
Which is both cheaper than the same number of hot-dog stuffed/ t-shirt wrapped, thawed chickens...and maybe more representative of little pest type critters.
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Haha, very true!
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On the topic of Hollow Points... the ultimate hollow point...
Back 35+ years ago, I would load pellets BACKWARDS into my S&W Model 77A .22 caliber pump-up... and at short range, those things were downright DEVASTATING! Gun was strong to start with, and a backwards pellet would flat out blow a bird to smithereens! lol
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I have been shooting at Limes :D
I had to cut away some of the lime tree's branches this year, and there not really ripe yet so I have like 10 lbs of targets...er un ripe limes :P
There surprisingly resilent.
Anyhow I shot some with domed pellets both H&N FTT and some Crossman Premiere and in both cases the pellet went clean through the lime about the same entry and exit hole size.
I shot one with a polymag and the lime nearly exploded! Big difference!
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As it happens, the sort of nut grey squirrels keep stealing from our tree is a rather decent testing medium for relevant pellet performance. Butternuts are an extremely hard, with a thick rind (before they get ripe - which is when the squirrels love them most) sort of walnut with relatively compact flesh, and are a bit smaller than the average squirrel skull. Penetration in a butternut is nearly the same as a squirrel's head. A bit easier to go through but it's something around 30% or so. I've found that a .177" wadcutter at 400fps will go through one side but usually not the other, and doesn't do a lot of internal damage. At 600fps the same 7.5gr wadcutter will make a hole on the far side about 4 times as big as the entry hole, and really tear up the inside. Has proven very similar on live quarry, with a neatly placed pellet at 600fps between eye and ear completely shuts them down, sometimes with far side penetration but usually stopped by the skin there and sometimes not even getting that far.
I've tested a 20fpe .22" 18gr JSB on the same nuts and they are obliterated, hollowed out and sprayed everywhere. Squirrels not quite as messy, but close. From the front the 20fpe will go through the head and down into the heart/lung region before slowing significantly.
So after this testing I opt for the 600fps .177" if they're at 10 metres or closer, 20fpe .22" if they're further out.
Tried other testing media, trying to build layered sandwiches simulating a squirrel's head, but the nut has been closest both in toughness. At lower velocities for example, a .177" pellet shot end-on to the nut and within less than 1cm of the upper edge of the outer flesh will just bounce off, as it does on squirrels hit between nose and eyes, so front-on shots are off the table except for the 20fpe rifle.
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Indonesian Limes (strong lime taste/ wringkly/leaves have a strong lime smelland tast, large thorns).
They dometimes get knocked to the ground, and I have shot them.
(http://i157.photobucket.com/albums/t50/ribbonstone/DSCF2249-1-1_zps684bcf63.jpg) (http://s157.photobucket.com/user/ribbonstone/media/DSCF2249-1-1_zps684bcf63.jpg.html)
Bad picture...the exit holes are harder to see... more like big rips at exit for the WC and HP.
Did put a short stack of pillows (Hosptital, use once and toss pillows) to cvapture the exiting pellets:
(http://i157.photobucket.com/albums/t50/ribbonstone/Image200-1_zps6ec219e4.jpg) (http://s157.photobucket.com/user/ribbonstone/media/Image200-1_zps6ec219e4.jpg.html)
Do have the best smelling back yard after a grass cut, as I'll toss a few fallen Limes out into the yeard and run over them when I cut the grass.
Same pellets as above:
Not as easy to see the difference in some spoiled hot-dogs (and kind of stinky), but the HP (Predator) pellet path is enough larger to confirm (the RN and WC paths aren't that much different).
(http://i157.photobucket.com/albums/t50/ribbonstone/DSCF2242-1_zps7bf70caa.jpg) (http://s157.photobucket.com/user/ribbonstone/media/DSCF2242-1_zps7bf70caa.jpg.html)
Not to wast much of anything, the above shot up/spolied hot dogs made for night time rat-bait.
MY use often includes WC's (even .22 wad cutters) so long as they shoot well.Not that they expand (if at all) but in low velocity impact (as you'd get with low velocity rifles or ot longer range with faster PCPs),but that the impact resuts are very prerdictaible....while HP'sseem to have some "bottom line" velocity for expansion.
Prediction: while there is still light out, will sacrifice another sweet potatoto the air-gun-gods.This time with a LOW speed .177 (like about 8 foot pound) PCP.
PREDICTION (and I'd be happy to find it wrong): the WC and HP won't be very far apart in exit holes.
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It would be great if there was a canolope or watermelon farm next to you.
I shoot the vegtables in my garden that dont ripen right
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Pass on the watermelon...don't have anything alive that is thick enough to warrant that....sticking with things more compact.
OK...one more for the "sweet potato" record.
(http://i157.photobucket.com/albums/t50/ribbonstone/f59756ab-89bb-4354-a990-3ae826616c00.jpg) (http://s157.photobucket.com/user/ribbonstone/media/f59756ab-89bb-4354-a990-3ae826616c00.jpg.html)
Get down in velocity to where it's right at 6 foot pounds of impact energy (really don't matter if it'sdown that low becasue you started at low speeds (like 8 foot pounds) and were shooting at short range (like 20 yards), or if you started at higher energy and shot at long enough rang eto where the impact energy was doiwn to about 6 foot pounds).
Basically, as in real life,really can't find much difference in terminal effects on "critters" when the speed of impact is down this low. Look as critically as you care to, but there really isn't "jack" difference between thre three.
So I tend to use WC's if they can shoot weLL in 20-30 yard back yard situations (if they happen to shoot well).....just too "stupid" not "slap" a critter and dump more ofthe energy inside a a little critters body thickness.
Next up, will try the same pellets at much higher speeds at impact. THINK I al;ready know that expanding pellets really do expand MORE with velocity (it has been the results in every test so far), and WEC poellets start to loose their accuracy with higher speeds (also has only been a once-in-awhile-"freak" pellet that brakes that rule).
But WHAT THE HAY.....if it's about tuening tweety birds into "buff balls" at 20-30yards, I could live with a lot worse MOA accuracy than the 100 yard shooters.
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Something a fellow air gunner and I have discussed was measuring the fpe that is spent in the target media.
The example we came up with was to choose a very common media that everyone could use as a standard, a beer/soda can full of water.
Chrony your different projectile at the muzzle first, then put you can of water at a desired distance with the chrony behind it. You may have to put a sheet of thin plastic between the two to keep the chrony dry.
Then you could measure the velocity of the projectile AFTER going through the media to get a true measure of energy being spent.
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Something a fellow air gunner and I have discussed was measuring the fpe that is spent in the target media.
The example we came up with was to choose a very common media that everyone could use as a standard, a beer/soda can full of water.
Chrony your different projectile at the muzzle first, then put you can of water at a desired distance with the chrony behind it. You may have to put a sheet of thin plastic between the two to keep the chrony dry.
Then you could measure the velocity of the projectile AFTER going through the media to get a true measure of energy being spent.
Sounds like a recipie for disaster ignore the fact that the chrony is probably going to get soaked, the pellet when exiting a can filled with water will be wildly erratic making good measurements nearly impossible. Also with murphy's law reigning the erratic pellet will most likely end up striking the Chrony itself.
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Interesting.... and glad to see I'm not alone in my odd testings.
I've done the same with those wretched Hickory Farms sausages I get each year at Christmastime. :-)
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I just wish you had some of the old Benji High compression(green tin) to do the test with... They were accurate to about 40 yards out of my Benji .22... they hit hard for two reasons... first is they had a large flat portion of the nose(meplat)... but flew well because of being semi domed... when they hit... being soft like JSBs they really buttoned out at the 18ish fpe I was sending them out at...
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Something a fellow air gunner and I have discussed was measuring the fpe that is spent in the target media.
The example we came up with was to choose a very common media that everyone could use as a standard, a beer/soda can full of water.
Chrony your different projectile at the muzzle first, then put you can of water at a desired distance with the chrony behind it. You may have to put a sheet of thin plastic between the two to keep the chrony dry.
Then you could measure the velocity of the projectile AFTER going through the media to get a true measure of energy being spent.
Sounds like a recipie for disaster ignore the fact that the chrony is probably going to get soaked, the pellet when exiting a can filled with water will be wildly erratic making good measurements nearly impossible. Also with murphy's law reigning the erratic pellet will most likely end up striking the Chrony itself.
You may have missed the sheet of thin plastic in front of the chrony. One could always cut a hole in a thick sheet of plywood say 2" so it could only pass through safely without nailing the chrony. You could also put the chrony behind the media farther as to not get any or as much over spray. Seems fairly simple.
With all the graphs and info on GTA and now even internal ballistics why would we still just be shooting fruit and vegetables for info without any form of measurement?
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While I appreciate the thinking behind shooting through an easily replicated standard medium to determine energy lost into that medium, I question the utility of a can of water. If the impact is identically centred every time perhaps this is valid. But considering how likely it is that impacts will be as much as 1" off centre for some shooters, the volume of water and angle of the aluminum impacted will vary dramatically.
Something more like a sheet medium would seem more appropriate. Especially something in a standard form, purchasable in any city (at least in Canada and the USA), is ideal. I was going to suggest shooting through standard thicknesses of Duct Seal (new putty only) such as 1/2" for lower powered airguns, 1" for higher power, etc. However temperature may play a role there. Still if used at room temperature (17 to 20 degrees Celsius) and if carefully rolled out to thickness that could be useful.
Another option might be to use a square plastic water bottle such that exact point of impact does not change penetration depth or angle of initial contact, reducing deflection and random energy dump variables.
Of course a chrony might easily measure the velocity of part of the punctured target, so the numbers could be questionable. A certain distance between chrony and target object seems wise... but then deflection and potential damage to the chrony comes into play again...
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How about a u shaped frame (say 12 x 12 high x across) that you could clamp a sheet of plastic like 6mil visquene, clear or black, on the front and back and fill the in between with water. You could make the thickness of the frame as thick as you wanted, 2", 3",... 8" and the water would be consistent resistance and you should be able to shoot it multiple times as the water slowly drains out of the front and back holes. Patchable with a good tape for that shooting session. And a 1/2 Lexan shield in front of the chronograph works, I use one right now. Bullets fly over the top but any low ones that would hit the chrony are stopped.
Actually, I built an 18 x 18 by 72 trough like this a few years ago to recover rifle bullets and see the expansion without having them stopped by something hard... Only problem was it took so many gallons of water to fill and with .457 400gr at 1800FPS it would only work once and the hydrostatic shock would blow out the plastic front facing window. Did it's job though, recovered perfect bullets at the back of the trough ( except a couple times the bullet vired off to the side and hit the side)
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Am looking for the orginal post...it's been like 7 years ago....
Crude Rube Goldberg type system to get an idea of energy deposited in a set thickness of test media (in this case,soaking wet news print type paper). Tried different calibers/pellets/energy levels/ and thickness of test media (the blow is actually a "thick" test).
(http://i157.photobucket.com/albums/t50/ribbonstone/DSCF0180_zps5285900f.jpg) (http://s157.photobucket.com/user/ribbonstone/media/DSCF0180_zps5285900f.jpg.html)
Idea was to shoot the system without the wooden box-frame holding the media to get the velocity (pellets impacting the green bag backstop dangling from the ladder) to get the average velocity. Then put the test media box frame in place and do it again to get the velocity of the pellets after exit.
From the average of those numbers, could figure out how much energy was deposited in the test media.
FOOT NOTE (wirth reading is you want to try this):
I did start the test with two chrongraphs, one ahead of the media and one behind the media.For COMAPARITIVE use, the slightl difference in distance wouldn't really matter as all the pellets tested had the same difference in distance.
BUT, about 90% of thw way though testing the calibers/rifles/pellets I wanted to test, one pellet just did not penetrate nearly as straight as I had hoped for....it took a dive somewhere in the thick media, missed the shielded front of the chronograph, but blew the back end of it to pieces.
So I ended the test with just one chronograph.
So do NOT bet that the pellets always penetrate in a stright line....they don't.
EDIT:
Still looking for the original....but do remeber that not too much unexpected was the result of all that.
With ROUND NOSED pellets that didn't deform/expand,was a pretty direct relation (inverse) between energy and setional density.
Was a pretty good (with some exceptions) inverse relationship between the pellet's BC and energy deposit.
Expanding pellets deposited the most.
In thin media (estimated pest bird thype thickness) often got more energy deposit with a 15 foot pound .177 Polymag than a 50 foot pound .25 RNL.
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Great info. By placing a sheet of plywood with a hole for the pellet to pass through ahead of the chrony would basically make a go/no go stop for them. If a pellet strayed too far off course it would simply smack the plywood and not the chrony. Media is definitely optional but I'm sure everyone reading this has an empty aluminum can and water on tap. And I'd have to assume that if your serious enough to go through this test that most would be able to consistently hit the center of a soda can at 50 yards or less. Even if performed at 20 yards, you'd have hard numbers that you could calculate for longer distances.
We've been using the cans of water to test how far out our hollow points will shoot and still open up. It helped us find the most practical use and yardage for them.
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Wouldent it be easier to come up with some sort of 'sled' that moved when struck by the pellet and somehow measure the movement?
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Wouldn't be nearly as easy to just cobble together as the above picture (which actuallly worked well).....but I'd avoid the sled and go with a pendulum with the test media to be penetrated as the striking point.
Yep...if I did the same test again, would use a shield BEHIND the test media to block any pellet that turned off courseinside the media.