My older son is getting set up to do a science fair project and he wants to do it on terminal ballistics. His current plan is to use his 54 Bobcat and PRB shot into damp clay. Due to the teacher mentioning something about developing as much data as possible but limiting it in terms of variables he is planning on using one powder level and just the PRB and doing 10 shots each at 15 yard intervals from 15 yards to 150 yards (100 shots total) and measuring the muzzle velocity (for ref.), depth of penetration and mushroom diameter.
I had thought about using a product from Midway (see it at this link http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=739849&t=11082005 ) but it would take forever to do the testing with only one and it would cost a fortune to buy a bunch of them so I guess the damp clay will have to do. I would also like to include more than one powder level and multiple bullets but this is his project and time is limited.
Like I said, he is still getting things together and working on his test plans so I thought I would post on here and see if anyone had suggestions on his plan or other ideas to test instead of what he is proposing?
Thanks in advance for any input.
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David
Only one man in a thousand is a leader of men -- the other 999 follow women.
Groucho Marx
It sounds like an interesting project. If you had a chronograph you could include that data as well.
Perhaps different powder charges, five shot tests, chronograph velocity readings, and then depth of penetration into the known substance at a know distance. Also if you could recover the ball you could add over all expansion for the forces exerted, on pure lead.
Good luck to your son...
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What will be the procedure? Shoot one shot, find it in the medium, record the data and repeat? Guess the medium (clay)would need to be remixed before another shot to eliminate the void from the first shot? Would it be better to use a spackle bucket filled with packed sand, complete with lid made of material, maybe tarp material, held in place by the lid from which the center has been cut, the bucket then turned horizontally? That way the sand would be held in place, the bullet would pierce the material, the medium would not have a void, the data could be collected and the material moved for the next shot and resecured with the lid. I wonder if a metal detector could be used to pinpoint the location of the bullet in the horizontal bucket to get that data, then dump the bucket through a rat wire "strainer" to another bucket thereby catchingthe bullet, and the lid resecured for the next shot?
What will be the procedure? Shoot one shot, find it in the medium, record the data and repeat? Guess the medium (clay)would need to be remixed before another shot to eliminate the void from the first shot? Would it be better to use a spackle bucket filled with packed sand, complete with lid made of material, maybe tarp material, held in place by the lid from which the center has been cut, the bucket then turned horizontally? That way the sand would be held in place, the bullet would pierce the material, the medium would not have a void, the data could be collected and the material moved for the next shot and resecured with the lid. I wonder if a metal detector could be used to pinpoint the location of the bullet in the horizontal bucket to get that data, then dump the bucket through a rat wire "strainer" to another bucket thereby catchingthe bullet, and the lid resecured for the next shot?
not costly, but measuring bullet depth is an issue. Expansion, weightand penetration were the primary variables. I have a MS in Statistics and to me you need to design a experiment with a couple of bullets and couple of powders and randomize the shooting so that you can do an "Two Way Analysis of Variance" on 3 variables,
penetration
expansion diameter
weight retention of the bullet
The "nulll hypothese you testing" is that "there is no statistially significant difference between a PRB and a "hornady XTP" with regard to
Penetration
Expansion diamerter
and WT retention.
That would be the experimental design I would do.
The experiment suggest by you or your son tests the null hypothese that there is no difference between distrance and penetration. You can do that with a "regression line" with the X axis being the distance shot and the y axis being distance penetration in the medium.
Chap
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Chapman Gleason
Purcellville Va
http://www.the-gleasons.com
Cayugad,
I do have a chrono and will be documenting the velocity. He also plans to document the post shot expansion of the bullet and the depth of penetration. His teacher is suggesting limiting the powder used to one load to reduce the variables.
Yeoman,
The procedure would be as you suggest, shoot one shot and then measure, recover, repack and next shot. It will be time consuming and I suggested he plan 5 range sessions of 20 shots each. I like the idea of using sand since it is easier to repack and maybe a little less messy than clay. I originally thought of clay in hopes of getting a retained wound channel but not sure if that would pan out.
Chap,
Give me more input. I like the idea of using multiple bullets for comparison and the same for different powder levels but my son doesn't want to get too many variables per his teachers admonitions. Maybe go with several different bullet designs at 2 distances and compare their performance would give fewer variables but produce useful results. What do you think?
__________________
David
Only one man in a thousand is a leader of men -- the other 999 follow women.
Groucho Marx
Cayugad,
I do have a chrono and will be documenting the velocity. He also plans to document the post shot expansion of the bullet and the depth of penetration. His teacher is suggesting limiting the powder used to one load to reduce the variables.
Yeoman,
The procedure would be as you suggest, shoot one shot and then measure, recover, repack and next shot. It will be time consuming and I suggested he plan 5 range sessions of 20 shots each. I like the idea of using sand since it is easier to repack and maybe a little less messy than clay. I originally thought of clay in hopes of getting a retained wound channel but not sure if that would pan out.
Chap,
Give me more input. I like the idea of using multiple bullets for comparison and the same for different powder levels but my son doesn't want to get too many variables per his teachers admonitions. Maybe go with several different bullet designs at 2 distances and compare their performance would give fewer variables but produce useful results. What do you think?
What is the null hypothesis you want to test? Different bullets penetrate differently at the same charge and same distance? or
Different powder type perform differently or different bullet designs perform differently, what do you want to test? Chap
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Chapman Gleason
Purcellville Va
http://www.the-gleasons.com
I will need to run all this by my son since it is his science fair project.
My prefrence would be to test different bullets at different powder/velocity levels as well as different distances (then again, different velocities could be used to approximate different distances based on impact velocity, hummm). I'm not sure. What do you think would be the most informative data to develop?
__________________
David
Only one man in a thousand is a leader of men -- the other 999 follow women.
Groucho Marx
Sounds like a pretty complicated process with a lot of work to keep the impact medium consistent.
Since you have a chrono, why not consider a simpler project such as a velocity comparison of increasing powder charges (5 or 10 grain increments)with the same bullet.
If he starts at around 60 grains and shoots 5-shot groups at 60, 70, 80, 90, 100, 110 and 120 grains (or even 60, 65, 70, etc.) it should show significant increases in the average velocityat the lower end of the scale and deminishing returns as the upper end is approached.
Still a lot of shooting and data, but not so much mud.
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Good idea, glad Ithought ofit. Great minds must think alike.Seriously, I tried to talk him into something like that but he wants to see what theterminal performance is, not just velocity. He even wanted to shoot 10 rounds at every 10 yards from 10 to 200 but I talked him out of that. I suggested 20 yard increments and we settled on 15 and shortened it to 150 yards.
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David
Only one man in a thousand is a leader of men -- the other 999 follow women.
Groucho Marx
Sounds like a pretty complicated process with a lot of work to keep the impact medium consistent.
That is true, but if you use potting soil as I did and a 10lb tamper your medium is pretty consistent, however the measurement into it would be the issue, most of my shots shot thru a 5 gallon bucket turned on it side with packed top soild, you could use two of them, but it is a lot of work to pick up the loose soil and retamp it into the 5 gallon bucket after each shot. However that is the only measure of "penetration", is something into some consistent medium, such as soil, sand or clay. Chap
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Chapman Gleason
Purcellville Va
http://www.the-gleasons.com
Science Fair anyone?
Seriously, I tried to talk him into something like that but he wants to see what theterminal performance is, not just velocity. He even wanted to shoot 10 rounds at every 10 yards from 10 to 200 but I talked him out of that. I suggested 20 yard increments and we settled on 15 and shortened it to 150 yards.
