Go to the end of the thread for the most recent test.
So my lovely and thoughtful wife bought me a 10mm Witness for Christmas and I've had a lot of fun working up loads for it. Problem is there really isn't a whole lot of terminal ballistic data available so I have no idea which bullets will hold together well or penetrate to what depth. I did a couple water tests but those were less than definitive and disappointing if the penetration results were to be believed. Worse, it seemed that they were inconsistent with other available data. So I decided the only way to get good data was to gather it myself. Here is my attempt at ballistic gel. Let me know how badly you think I did.
Proper ballistic gelatin is 10% by weight 250 bloom photographer's gelatin. That means 10% of the weight is gelatin and 90% of the weight is water. It is kept at 39° F and is calibrated by a .177 cal steel BB at 590 fps +/- 15fps. The calibration shot(s) should be between 2.95"-3.74". 250 bloom photographer's gelatin is expensive so I bought grocery store unflavored gelatin. I did the math and found that 10% should put me at about 1 cup of water per ounce of gelatin. I bought three 8oz packages of Kroger gelatin and mixed it up with 24 cups of water but it didn't calibrate correctly. I bought another three 8oz packages, Knox this time and mixed it with 18 cups of water, melted both batches down and mixed together. So that's a total of 48oz (by weight) of gelatin with 42 fl oz of water.That got me close to what I was looking for but I had to melt and add water a couple times again. The final mix was 48 oz gelatin to 45 cups water. I've since doubled the batch and confirmed that ratio, but if you make some up, it might be better for you to start a cup or two short just because it's easier to add water than remove it. My procedure follows.
Open all the packages into a bowl for easy pouring. Measure 45 (or a bit less) cups of hot tap water (I have since found that cold water produces less clumping so I mix it cold and then heat in a double boiler) into a bucket, along with a few drops of bleach (to prevent mold) and a few drops of Jet Dry to prevent foaming. Start the water moving with a mixer and slowly pour in the gelatin. Be careful to pour slowly enough to avoid clumps but some are probably inevitable. Allow to cool and refrigerate for about a day. Heat in a double boiler until just melted, stir, and pour into molds. Allow to cool and refrigerate again for several days. It gets firmer after several days and it has to be all the way down to 39° throughout for calibration to have any meaning. Fire a 590 fps +/- 15 fps .177 cal BB into the block and measure the penetration. In the picture below, the bottom shot took place at about one day in the fridge and it measured 4". The shots above that took place at about three days and measure, bottom to top: 3", 3 1/8", 3 1/4", 3 1/8". The other picture was a .22 cal pellet from a Benjamin Sheridan pellet rifle just for fun. It penetrated 4 1/2".
After a test, I cut the blocks to get good photos of the "wound" track and put them in a double boiler to remelt. I just use a plastic bucket (about 2 gal, I think) for the gelatin and a large stock pot for the water. I keep the stove on medium and try not to let the gelatin completely melt while it's in the water. As it melts, I pour it out and add more blocks to keep the temperature from getting too high. When I'm down to the last of it, I remove it from the heat before it's completely melted and let it finish melting on the counter. The warm gelatin is usually enough to melt a few smaller chunks. I pour through a wire mesh grease splatter screen first to remove the larger chunks of denim, dirt, lead, copper, and BBs, then I pour through a "permanent" wire mesh coffee filter to remove the smaller particles. It all goes into a large bucket until it's all melted and then into the molds. For molds I just use cheap Sterlite tubs from Walmart.
Here's a new test with a bit more precise data:
BB calibration: 590.8 fps, 3" penetration
.22lr from Walther P-22: 36 gr CCI Mini-Mag hollow point at 970.0 fps, 8 3/8" penetration
I got distracted by something shiny and forgot to place 4 layers of denim in front of the .22lr shot.