Fun to shoot, not too difficult for the hobbyist to make, and if you follow the directions and calibration procedure closely, you can get fairly accurate test results.
So you want to see what might really go on with the self-defense ammo you have purchased, or how your hand loaded ammunition stands up head to head vs commercial products. Just go to the range and shoot up a block of ballistic gelatin, right? Sure.. but where are you going to get it?
A brief look online shows some clear pre-formed synthetic ballistic blocks that you can buy. They seem to be rather expensive, and limited chances for re-use. That means you have to make your own. When shopping for ballistic gelatin, most internet searches point to VYSE or Custom Collagen. Good stuff, and as expected, not super cheap. More exhaustive searches may turn up other products. I have found bulk bagged ballistic gelatin kits sold at gun shows before. I purchased some a while back. No manufacturer info, just some photocopied directions, and bags of powder. ( They also sold cardboard fold together molds and bag liners for the molds. ) With a little searching on the internet, you can find places online selling kits such as these.
Another option is to use commercially available food grade gelatin. I was skeptical at first but recently tried an A/B test with some of the commercial gelatin and food grade using a .380 as a test gun. Both gelatin’s calibrated approximately the same and I feel the food grade gelatin if you follow good procedures making it and testing it, will be a good medium for the average hobbyist wishing to test their ammunition without breaking the bank.
What you will need:
Knox unflavored gelatin powder. A paint stir stick or plastic spoon to stir with. Preferably a large multi-gallon stock pot, a large mixing bowl, refrigerator space ( not freezer ) sufficient to hold your gelatin mix during preparation while in a bowl, and when in a form, cinnamon oil ( optional ), propionic acid 5ml per liter can be added to inhibit mold growth ( optional ), water measuring device, kitchen scale ( possibly optional ), cardboard or other form material, duct tape, a liner bag that is watertight for your mold, mold release spray, a food grade pot coating will work, cooking thermometer capable of reading in the 100-150’ F range.
You can buy the powder in 8oz boxes ( inside separate packets ), or in 1 pound tubs. If you look online, I have even seen 24-ounce packages.
Depending on who’s product you are using, or where you look on the internet, you will find a few different methods of preparing the gelatin. I looked at a few of them, and their outcomes, and decided to go with a modification of some of the most common instructions.
First, you want to try to keep your water and gelatin mix at the correct ratio to mimic the 10% ballistic gelatin. ( which is supposed to simulate swine muscle tissue ). After a few test batches, the following mix rates seemed to work the best for me. 8oz of gelatin powder per 2 quarts of water. ( 16 oz per gallon, 20 ounces per 1.25 gallons, etc. ) . Before you buy any gelatin, get an idea of the mold size you want to make or use. Figure it’s cubic inches. I like rectangular molds. L x W x H in inches = cubic inches. For instance, a mold that is 5” x 5” x 12” is 300 cubic inches. Next, convert cubic inches to fluid ounces. ( 1 cubic inch = .5541 US fluid ounces ). Thus 300 cubic inches = 166.23 fluid ounces. A Gallon is 128 ounces, 1.25 gallons is 160 ounces. And 1.3 gallons is 166.4 ounces. Thus 20.8 ounces of gelatin powder will mix with 1.3 gallons of water for a 300 ci mold. You can use these numbers to make larger or smaller molds. Mixing tub and refrigerator space will probably be your main limiting factors. These gelatin blocks, once finished, must be refrigerated until use.
Start with cool or cold water. Sprinkle your powder into the water, don’t pour the water into the powder. You will entrain too much air pouring the water into the powder. Slowly stir, don’t whip, and try to not get extra air into the mix. Use your hands to break up the clods as best you can You won’t get them all, usually not even close. Melting:
Put your mix into the fridge. You ideally want 35-40’ F. Let it set at least 2 hours, but 4-6 is fine. You are letting the gelatin hydrate. After it has hydrated, pop it out of your bowl onto a cutting surface, it should be a big gelled clump that looks more clear at the bottom, with opaque clumps at the top. Take something like a steak knife, and start sectioning the block into thin pieces, say, ½” thick or less. The thinner they are, the easier they melt. A steak knife seems to cut good since this is simulating animal tissue. Note that in this form, the gelatin has not reached its target viscosity.
Set up a double boiler. IE, a large pan or pot with a few inches of water in it, and another pan floated in it. Place your gelatin strips in there and let them start to melt. Ideally, your gelatin melt will not get over 104’F, but I have gone higher with no ill effects. Keep your double boiler water under 130’F and this should help prevent overheating the melting gelatin in the center pot. Keep adding and stirring slowly till your gelatin is melted and clear.
I used a cardboard box mold. I just found something that happened to be the correct size. You can simply make one with cardboard and duct tape. Find a bag to use as a liner that will be water tight. You can also use other things for forms, anything that you can get the molded gelatin to dump out of really. Smooth sides are best. Use a cooking oil spray as a release agent.
Pour your gelatin into the mold carefully so as to not to capture air. Some gelatins foam more than others. If yours foams excessively, a couple drops of cinnamon oil on top will let you spoon the foam to an edge. Don’t mix the oil into the gelatin. Also, keep in mind that if you do not contaminate the gelatin with dirt, etc, that after you shoot it, you can re-melt it and remold it. To help it last, add the propionic acid mentioned earlier to inhibit mold growth. You could get quite a few uses before you have to toss the batch.
Once you have it poured, put it in the fridge and wait at least 36 hours. If it is a huge 1’ x 1’ x 3’ mold, go 48 hours. If you have any excess mix, pour it into a small container and use this as your BB test block. A plastic drinking cup can work good or a disposable plastic food container.
First, you will want to calibrate your gelatin. You use a 17 caliber BB gun fired at about 590 fps, give or take about 20 fps. You are looking for 8cm of penetration. A range of 7.9 to 8.6 is fairly acceptable for hobby gelatin approximating 10% Gelatin like the FBI tests with. Remember, as soon as you take your block out, it starts warming up, so test it cold, and do your shooting tests with it cold. As it warms up, it will get softer. So keep it in the fridge till needed, then pack it in a cooler for the ride to the range. A cooler with some soft cold packs works well. Avoid ice, as it will make cold spots and effect density.
Shooting:For smaller blocks in the 8-12” thickness range, many people get creative and lay a couple layers of fabric over the front of a block, and put a board or drywall behind it. Keep in mind that anything in front of the block goes into the block, so you can contaminate your block easily. So you might want to do some straight shots and remelts before you do your clothing shots.
I’ve had the chance now to make a few mold designs and shoot a few blocks. One mold I love is a 2L plastic bottle mold. It uses very little product, just 8 oz gelatin, and 2 quarts water, so it only costs about 9$. You take a 2L bottle, melt some candle wax or canning wax. Set the bottle in a shallow pac with some ice and water to cool the bottle base. Pour in the wax using a funnel so that the nubs in the base of the bottle are covered up, and the curvature of the base is near the full diameter of the bottle. This will give you a smooth face to your gelatin, and takes up some of the volume, since a 2l bottle can hold .53 gallons. When you fill with your gelatin mix fill only till the bottle starts to taper in, you will likely have a small amount of mix left, pour that into a disposable drinking cup, you may have enough for your calibration test. When your mold has set up, use a sharp knife and cut the bottom out of the bottle, right at the union of the wax and the gelatin. Cut on the wax side so as not to damage the gelatin, pry out the wax and save it to re-melt and re-use. Remove the cap on the 2L bottle and the gelatin should slip right out.Tip, if you are re-using your gelatin after shooting it and get small debris in it, wood chips, bullet jacket fragments, etc, pour thru a coarse strainer when you get near the end of the pot containing the debris.