ORIGINAL: dmurphy317

My son is still gathering data and the final results may take another two weeks to finish but I couldn't resist posting some of the results of the first round of testing. His teacher wanted him to only have one variable for the science fair so he picked 3 different size bullets as that variable. The bullets chosen were all 54 cal and included the .535 round ball, 310 grain Buffalo Ballet and home cast 410 Maxiball.

The test setup included a chroney for velocity of impact, each bullet weighed before and afterwith each shot into a container of damp clay. The depth of penetration and amount of expansion were measured todetermine the performance of each round. The retained weight was also a data point tracked.

What I wanted to do was to test at 3 different powder levels to similate different impact distances but we did not have time on the first session. It took much longer to dig the bullets out of the damp clay than we had anticipated. We had a total of 11 usable shots in 5 hours (a 12th shot was unusable due to a malfunction of the chronogragh). The fact that it was averaging right around freezing didn't help with the damp clay either. I nearly got frost bite digging in that cold clay.

We hope to do a little more testing next weekend if I can get back home, did I mention I'm having to travel alot these days? Any way, here is the data so far, I'm still waiting for my son to finish measuring the expansion.

.535 round ball, 5 shot averages
velocity = 1225fps
pre weight = 15 grams (231.5 grains)
post weight = 14.92 grams (230 grains)
% retained = 99.3
penetration = 8.8 inches

310 grain Buffalo Ballet, 3 shot average
velocity = 896fps
pre weight = 20.07 grams (309.7 grains)
post weight = 19.93 grams (307.6 grains)
% retained = 99.3
penetration = 11.25 inches

410 Maxiball, 3 shot average
velocity = 925fps
pre weight = 26.6 grams (410.5 grains)
post weight = 26.43 grams (407.8 grains)
% retained = 99.3
penetration = 16.17 inches

The testing was done with 60 grains of Pyrodex RSat 5 yards so the velocities are basically impact velocities. We are hoping to finish the 4th and 5th shots for the Ballet and Maxi's next week if everything works out. I may even get to do a few shots at the other powder levels if we have time. You will notice the Ballet's were a bit slower than the Maxi's, I think that is due to the hollow base Ballet's may not have obturated enough to fully seal the bore with such a light powder load, they also had the largest spread in velocity, 200fps. Also at these impact velocities the Maxi's didn't really expand much if any but with 16+ inches of penetration who needs expansion. The Ballet's also had some that didn't expand much but I think that has to do with the impact velocity varying so much.

One other thing I did as a reference, but it may not be valid, was to shoot one shot into the clay with my 30-30. The 150 grain bullet only penetrated about 8 inches but the impact velocity was 2490fps so it was too high to similate a normal range shot. I may need to set the container out at 100 yards and try that again to see what kind of penetration it get at a lower velocity. I do have to say the 12" diameter crater it created was impressive, none of the ML loads came even close.

More to come as he gets the other things done. Maybe even some pictures when I get home and download them.