Thanks. I also found out that the regular gelatin will rot and smell horrible
Yes, it will. It is biological. I have heated it and reused it on a limited basis. Can be a PITA. I still have a few bags of it.
Most of my testing is with Fackler boxes. IMHO, the easiest and simplest to use.
The “Fackler” box is named for Dr. Martin Fackler, a wound ballistics professional whose work in his field has lead to the almost universal use of 10% gelatin to simulate flesh. Fackler experimented with several mediums. A Fackler box is simply a long, wooden box in which a row of plastic Zip-Loc bags full of water is placed. The bags are fired into from the test distance to obtain bullet penetration and expansion information. For comparative purposes, water works fine, but the amount of bullet penetration you get in water will have to be measured in inches and multiplied by 0.56 to equal its penetration in gelatin. Water is a very hard medium for bullets and may tend to cause light, high velocity bullets to shatter.
For slower projectiles, it works okay. When I sought to increase the utilization of fackler boxes, I tried a variety of things, which is, in fact the beauty of Fackler Boxes. I have been able to make representative stacks by using fresh Deer skins and bones mixed in with the bags of media to get a better representation of real performance. Having a vacuum packer helps a good deal.
I tried bags of ballistic gelatin, glycerin, water with shredded paper, glycerin with shredded paper. For general use, water with shredded paper works really well. Glycerin with shredded paper is really close to ballistic gel, enough so that one can pretty much compare with Ballistic Gel. I made a metal rig that resembled a miniature monkey bars and used clips to suspend the bags over a metal tray that had a screen covered hole and spout to drain the Glycerin back into a bucket. That is more than you probably need, but when I started shooting .308 slugs into my plywood constructed box, it did not take long before I blew it apart.
Shooting subsonic pistol rounds, if I wanted to look at bullets, I'd use the number of bags penetrated then hang a heavy sheet of 7 ply rubber at the end above a bucket. I'd just clip in new bags and shoot 10 or so and have a nice pile in the bucket at the end of the box.
I've not shot into a Fackler box in about 5 years and it is about time to make a new metal one.