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Posted: 3/31/2013 7:27:00 PM EDT
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So I've bee considering doing some very basic ballistc testing with a few different calibers to get an idea of real world performance after a bullet passes through one or more walls. I was planning on constructing some 4 ft squares just like the internal walls of a house (1/2 in drywall, studs on 16 in centers) and setting them up at 12 ft intervals (approximate length of an average room) and shooting them from typical home defense ranges with a couple handguns, an ar15, and a 12 ga shotgun to compare penetration performance.
I realized that penetration alone doesnt provide much information, and that it would be much more useful to have projectile weight and velocity after passing through each "wall". Heres where I need some help, I dont have the equipiment for proper ballistic tests (ballistic gelatin) so do you guys have any suggestions for stopping the bullet after going through a wall without any additional loss of weight? I was thinking maybe a series of milk jugs full of water but I didnt know how this would effect the bullet weight wise. My other problem is measuring the velocity after the bullet passes through the wall. I'm kinda scared that if the bullet fragments or is deflected somehow I might end up shooting my chrony. Also depending on how many walls some of the handgun rounds go through, I dont know if I trust my shooting ability enough to not hit it. If anyone has any suggestions or knows of any tests like this that have already been done it would be much appreciated. Whenever I finally get around to doing this I'll document it all and probably record it and post it all here. Thanks, Paradax |
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I give their dry wall test a massive "fail". As the OP indicates spacing is important, especially with rounds that tumble and shed velocity, as they need a realistic distance to do both and the boxotruth folks did not do that. With proper wall spacing I think it's quite likely you'll get a fair degree of deflection with .223 rounds and a chrony would be at some risk. I'd suggest shooting on a cloudy day when no sky screens are needed, set the chrony fairly low to increase the area it will read and then protect it with a piece of angled steel plate. That's what I do when measuring BCs with two chronographs one at 10' and one at 310' - the downrange chrony is placed behind an angled AR500 steel target. It's cheap insurance. 3 or 4 gallon milk jugs will stop most pistol rounds and will probably stop a tumbling .223. You'll want to set them down range of the chrony to keep it dry and you may consider putting a sheet of plastic between the chrony and the water jugs to reduce splash on the chrony. You can also use 1 pound of Knox gelatin per 1 gallon of water to make something close to ordinance gelatin. You need to mix it and then let it hydrate in the fridge for a couple hours, then heat it on a stove (stirring it carefully to avoid trapping air bubbles) keeping it below 130 degrees F. They refrigerate it for a couple days, take it to the range in the mold in a cooler, remove it from the mold and shoot it. If you keep it on a table (like an X-table) you'll be able to keep it clean enough to remelt and re-use after you remove the bullet and any fragments. Total cost will be $10-$15. |
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