No real relation to reality....sweet potato test

[Kinetic45^]

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)

[Ribbonstone]

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).



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.

[swish]

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.

[UlteriorModem]

Wouldent it be easier to come up with some sort of 'sled' that moved when struck by the pellet and somehow measure the movement?

[Ribbonstone]

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.