ORIGINAL: dmurphy317
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?
In my mind the most informative data to develop is bullet differences, since that is what most people are interested in. Differences in powder, we know that one is more powerful than another by semisane shooting same volume of 777, goex, shockey gold, etc and gettting different velocities. Bullet design (round, hollow point,ballistic tip) is the experiment I would do and measuring penetration, expansion and weight retention %.
Different bullets at differnt velocities, all other variables are derived from these two, measure penetration, expansion and Wt retention. This is a "2 factor experimental design" with the randomization of bullets to the "treatments", this is all just fancy statistical lingo to say shoot the bullets in a way that biaes don't creep into your experiment. Lets say we have 10 round balls, 10 Horndary XTP and 10 TC SW, and lets say the weights are about the same 200g, since the Round ball is 190 or something like that. Lets say we have the following 3 levels of charge
50g
75g and
100g
use the exact same swabing method between shots, use the exact same primer, exact same powder. Now randomize the experiment by taking 3 pieces of paper the same size and writing 50, 75 and 100 on different pieces. Take 10 round balls, 10 Hornady XTP and 10 shockwave and put them in a hat mix them up.
Pull the first one out. reach into the 2nd hat and pick out a piece of paper, say it had 75 g on it, so bullet 1 is shot at 75 grains and then 3 measures are made: depth into sand
expansion diameter furthest point to furthest point
weight retention %
Label that bullet bullet 1 by placing in a plastic bag, with the measurements.
Pull 2nd bullet out at random, say it is XTPreplace the piece of paper from bullet 1 and mix it up have another person pull a piece of paper from the had, say that is 75g again.
do this for all 30 bullets
you will get a data matrix like this:
bulletshot at penetration expansion weight
RB 75g 4.3" .73 187g
XTP 75g11.7" .65 196g
etc
I will send you the formulas and your son can do the statistics for an "F-Test" to test the Hypothesis of no statistically significant difference between bullets for penetration, weight retention or expansion.
Chap