How to make ballistic gelatin
Today's blog is actually a comment sent in by pestbgone. I liked it and several of you did, too, so I made it into a posting.
B.B. and others, Thought I'd offer this in case anyone is interested in a fun winter garage project. I apologize for the length. BALLISTIC GEL recipe and procedure: I got this info from Custom Cartridge, Inc. I kept the same formulation but modified the procedure to something suitable volume-wise for airguns. It's not difficult, but it takes a lot of time to do it right.
Materials: Clear (not frosted) plastic storage box approx 12" x 6" x 3" deep One 8 oz. box of Knox Unflavored Gelatin (has 32 1/4 oz. pkts) (Don't use JELL-O because it has sugar/sweeteners and won't give consistent results) 10 cups hot water. Large stainless steel sauce pan. Wire whisk for stirring. Gravy separator like this: NORPRO from Kitchen Emporium. Fine-toothed hacksaw
Mixing: This makes 10 cups of gel, which will fill the plastic box about 2-1/4" deep. Open all 32 pkts (8 oz.) of the Knox gelatin and pour them into a drinking glass. Put exactly 10 cups of hot water into a large stainless pan on the stove. Heat the water just hot enough so you can't put your fingers in it, about 140F, and TURN OFF THE HEAT. Do not boil! Start stirring with the wire whisk and SLOWLY sprinkle the Knox into the water, a tiny bit at a time. Adding too much at once will make it gum up into balls and you'll have a useless mess.
Keep stirring. Don't use an electric mixer because it will put too many air bubbles into the solution. Periodically, use a slotted spoon to remove the foam and scum. It will take 10 or 15 minutes hand stirring to add all 8 ozs, but you can take a break if you need to. After it's all mixed in, let it set for a few minutes so the fine bubbles will rise and then skim off the rest of the foam.
Now move the pan to the kitchen sink so you don't make a big mess. To get the clearest gel, use the gravy separator to transfer the solution to the plastic box like this: use a cup to ladle some of the solution from the pan to the gravy separator. Pour off the scum from the separator back into the pan, and then slowly pour the clear solution into the plastic box. Repeat until it's all transferred. Let it sit on the counter for a while and skim off any remaining bubbles that rise to the surface. Put it in the fridge overnight; do not freeze. BTW, this stuff will keep in the fridge or a cold garage for a couple of weeks, especially if you keep it covered, but will slowly start to dehydrate.
Set-up for shooting: Here's the trick. You can leave the gel in the plastic box for all of your shooting by carefully sawing off one end of the box with the hacksaw. You shoot length wise into the open end. Just be careful not to crack the plastic or get a bunch of plastic shavings on the surface of the gel when you are sawing.
I set up a solid rest for my gun and first shot through pieces of cardboard to simulate the front and back end of the gel box. I shot at 8 feet, but closer might be easier. Don't kid yourself into thinking you'll be able to aim with the gun sights. Repeatability of the shot location is vital. After you know exactly where your gun will put the pellet, lay a board down flat to hold the gel box at the right height, azimuth, and elevation. I was able to fit nine shots across the 6" width and make an upper and lower level of shots for a total of about 18 shots. But you have to use reference lines to index the box of gel over a little each time and keep it parallel both vertically and horizontally to the path of the pellet.
Shooting: Use your index lines to move the box over and/or up or down with each shot. I was only shooting with .177 cal, and found that wadcutters and HPs tended to move the box, so I weighted it down with a clean board before each shot. Domed pellets moved it less. I imagine .22 would make it hop around more, like the .22 rimfires I've done the same way. For reference, a Crosman Premier 10.5gr domed penetrated 11.2" on average.
Photos: The Custom Cartridge, Inc site has good info about taking photos. Lighting is critical and for me, good sunlight was the easiest way to get good lighting.
Have Fun: No instructions needed!