Brass Fetcher Ballistic Testing
Many misconceptions exist in the area of understanding how a bullet actually damages the target and which physical mechanisms are important to this process. I have addressed in other areas of the website the primary wounding mechanism of a bullet, which is the direct crushing of the tissue that is in contact with the penetrating bullet. Here we take a look at some of the different theories that address other potential wounding mechanisms.
In the early 1990s, when international combines and their political puppets in the United States were pushing for civilian disarmament, the topic of temporary cavity was introduced in the publics mind. Anti-gun news media portrayed the wounding effect of so-called “assault weapons” as being capable of ‘making a hole the size of a grapefruit in someone’s chest.’ Like all propaganda, there must be a seed of truth in what they say and there was. There are 4 dimensions that we can easily measure: length, width, height and time.
The kernel of truth in the propaganda is that rifles are capable of making a hole this large for about 7/1000 of a second and then the tissue collapses back to its original state with little damage. This, of course, was not mentioned in any broadcast that I am aware of. The report that follows below is an analytical study that I have done using slow motion video to measure the temporary cavity of many popular handgun and rifle cartridges.
The first time I heard the ‘spinning bullet’ theory was from a bouncer who was trying to sell me on how I should buy a “10mm Glock” when I got old enough to buy a gun. His reasoning was literally that it is the only gun in the world capable of spin-stabilizing a bullet (never mind the fact that all rifle and pistol barrels have … rifling … cut into the barrel which is what spin-stabilizes the bullet) and that this spinning motion would suck organs from all around the body out of the exit wound. (See full report: Temporary Cavity)
Not having gone through mechanical engineering school at the time, being 15 years old and so forth, I was both intrigued by the possibility of wounding being done by the rotation of the bullet and what this portends for being able to wound in the case of a near-miss of a vital organ. There is, in fact, sizeable potential for bullets to enhance wounding due to the fact that moderately-powerful handgun cartridges expend nearly 50 ft-lbf of kinetic energy to rotate the bullet in the barrel for stabilization on its travel towards the target. In the report below I focus on 9mm Luger and 45 ACP handguns. Wounding done by rifles and other high velocity missiles can be expected to be far greater than handguns. (See full report: Bullet Spin)
A shockwave is formed when an object is struck by another object that is in motion. There is an idea that this shockwave is capable of causing damage to organs long before the bullet can physically touch them. To get an initial read on this potential, before further and more in-depth tests are conducted, I embedded a raw chicken egg into a gelatin block as the solution was cooling. The shockwave is more likely to appear with a high velocity projectile that transfers all of its kinetic energy over a shorter-than-normal time period. A fragile varmint bullet was in order and the 22-250 Remington that I had available met the bill. The video illustrates a slight amount of damage to the egg, possibly caused by the shockwave.
Ballistic gelatin is made from the dried connective tissue of pigs. Its proper name is 250 Bloom Acidic, porcine gelatin. I suspect the reason that more people don’t shoot ballistic gelatin is that it is expensive to get started, messy and sometimes tedious to prepare a large number of gelatin blocks. A completed gelatin blocks lasts me four days in the refrigerator and it can only be out of refrigeration for a few minutes in a warm climate.
A number of companies have developed and are developing synthetic versions of ballistic gelatin. The vendor usually claims that their product is:
- 1. A duplicate of 10% ballistic gelatin in terms of penetration depth and bullet expansion.
- 2. Indefinitely Shelf-stable
- 3. Recyclable
To date, only Clear Ballistics has contacted me to inquire as whether I wanted to evaluate their product. So I did. I shot their block with a 223 Remington hollowpoint and I shot 10% and 20% gelatin with the same ammunition. (See full report: Clear Ballistics)