I've messed with ballistics gelatin a little in the past, and even had a dedicated fridge for it. It's a cool medium but it turned out to be too much hassle in the end. It was too expensive to get enough for testing multiple rifle or shotgun rounds in one trip to the range. One shotgun slug and the whole 10 gallon batch would be done for the day. Remelting took a whole day and when it froze it was almost impossible to recycle as the water would crystallize out and leave huge pieces of hard gelatin. I think I'm done with ballistics gel as long as I'm too poor to afford a 300lb drum of it.
A few alternatives that we've probably all heard of are wet phonebooks, water jugs, clay, homemade play-doh, pork roasts or dead pigs, some special waxes, and that very expensive Perma-Gel. Of course all of these are out of the question for most serious testing for various reasons whether they be limited practical availability, poor consistency for a tissue simulant, poor visibility of results without a high-speed camera, etc.
I don't believe that good ballistic test media necessarily need to match the exact properties of muscle tissue to be of value; in fact I would argue that ballistics gel would be a better test medium than actual animal carcasses because it is consistent throughout and will give repeatable results allowing accurate comparison between one round and another. Probability plays too much of a role in the non-homogenous structure of an animal and could easily make a lesser round appear to beat a superior one if it did not strike any bones or tendons or just went through different muscles. Of course in real life that probability does come in to play, but the best all-around loads should be found by testing on a variety of barriers/bones/etc placed in front of or inside the same consistent medium and looking at the average results.
With that in mind I think all that is really important is that the medium is consistent, can support its own weight in target-sized blocks or at least some very cheap container, and contains a majority of liquid content with a similar vapor pressure to water so as to exhibit the same cavitation effects. At least some elasticity may or may not be desirable too.
Regardless of the actual differences in penetration, temporary and permanent cavity size in an alternative medium to ballistics gel, it should be possible to come up with correction tables that would be able to correlate the results to gelatin at least for any given projectile type. Obviously in more plastic media the permanent cavity size will be impossible to see, but permanent tissue damage can be estimated at least roughly by the recovered bullet and knowledge of crush cavity size compared to bullet diameter with various geometries.
I am curious as to what if any other media people have tried, and how they worked. I tried the play-doh thing - a cooked mixture of flour, salt, water, and oil, but it is not so easy in the large quantities needed to test rifles and shotgun slugs. My batches came off the stove at a perfect consistency but then turned way too sticky to handle and lost all elasticity some time after it cooled down. I put a lot of hours into trying to cook it more and make it work again but no luck. I suspect that it got too cold during a trip to the range and the salt crystallized making it very hard to reconstitute.
I think, though, that I may have hit on a good one now. It is made of cellulose blow-in insulation, the kind that is made from ground up newspaper, soaked in calcium chloride brine as an antifreeze with similar physical properties to plain water. So far my shots into this medium have demonstrated too great of expansion, as if shot into straight water. Also the penetration was slightly high compared to gelatin, but not outlandish. The medium as-is also requires containment with tarps or such so as to not explode, but this is trivial as it does actually support itself with the open cavity if it is wrapped. It is somewhat over-saturated making handling tricky and I think that straining it out to a lower brine content may improve all of these problems at once. The medium is certainly dirt cheap, fairly consistent, and relatively easy to reconstitute after each shot.
A few alternatives that we've probably all heard of are wet phonebooks, water jugs, clay, homemade play-doh, pork roasts or dead pigs, some special waxes, and that very expensive Perma-Gel. Of course all of these are out of the question for most serious testing for various reasons whether they be limited practical availability, poor consistency for a tissue simulant, poor visibility of results without a high-speed camera, etc.
I don't believe that good ballistic test media necessarily need to match the exact properties of muscle tissue to be of value; in fact I would argue that ballistics gel would be a better test medium than actual animal carcasses because it is consistent throughout and will give repeatable results allowing accurate comparison between one round and another. Probability plays too much of a role in the non-homogenous structure of an animal and could easily make a lesser round appear to beat a superior one if it did not strike any bones or tendons or just went through different muscles. Of course in real life that probability does come in to play, but the best all-around loads should be found by testing on a variety of barriers/bones/etc placed in front of or inside the same consistent medium and looking at the average results.
With that in mind I think all that is really important is that the medium is consistent, can support its own weight in target-sized blocks or at least some very cheap container, and contains a majority of liquid content with a similar vapor pressure to water so as to exhibit the same cavitation effects. At least some elasticity may or may not be desirable too.
Regardless of the actual differences in penetration, temporary and permanent cavity size in an alternative medium to ballistics gel, it should be possible to come up with correction tables that would be able to correlate the results to gelatin at least for any given projectile type. Obviously in more plastic media the permanent cavity size will be impossible to see, but permanent tissue damage can be estimated at least roughly by the recovered bullet and knowledge of crush cavity size compared to bullet diameter with various geometries.
I am curious as to what if any other media people have tried, and how they worked. I tried the play-doh thing - a cooked mixture of flour, salt, water, and oil, but it is not so easy in the large quantities needed to test rifles and shotgun slugs. My batches came off the stove at a perfect consistency but then turned way too sticky to handle and lost all elasticity some time after it cooled down. I put a lot of hours into trying to cook it more and make it work again but no luck. I suspect that it got too cold during a trip to the range and the salt crystallized making it very hard to reconstitute.
I think, though, that I may have hit on a good one now. It is made of cellulose blow-in insulation, the kind that is made from ground up newspaper, soaked in calcium chloride brine as an antifreeze with similar physical properties to plain water. So far my shots into this medium have demonstrated too great of expansion, as if shot into straight water. Also the penetration was slightly high compared to gelatin, but not outlandish. The medium as-is also requires containment with tarps or such so as to not explode, but this is trivial as it does actually support itself with the open cavity if it is wrapped. It is somewhat over-saturated making handling tricky and I think that straining it out to a lower brine content may improve all of these problems at once. The medium is certainly dirt cheap, fairly consistent, and relatively easy to reconstitute after each shot.
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