WOUND BALLISTIC REVIEW
JOURNAL OF THE INTERNATIONAL WOUND BALLISTICS ASSOCIATION
SIMPLIFIED BULLET EFFECT TESTING
Martin L. Fackler MD, Wound Ballistics Consultant, Hawthorne, FL Abstract
PURPOSE: To describe a simple and inexpensive test for handgun bullet performance
METHOD: Bullets are fired through a single halfgallon cardboard milk carton filled with water, backed by a twenty-six-inch long cardboard box filled with unspun cotton fibers.
RESULTS: The four inches of water causes a handgun bullet to expand as it does in living tissue. Then the cotton fiber material wraps around the bullet and stops it from recovery while causing it no additional deformity
CONCLUSION: The resistance to a bullet's penetration in water mimics closely the deformation-causing potential in living softtissue. Unspun cotton fibers capture a bullet without causing it to deform or fragment. Since the cotton can be reused indefinitely, only a single onehalf gallon milk carton needs to be replaced for each new shot.
Ordnance gelatin mixed in a 10% by weight solution and shot at a block temperature of 4°C has become the standard for reliable and reproducible testing of bullet effects. Each block of the gelatin must be calibrated before test shots by shooting a steel BB into it at 590 ft/sec. A BB penetration of 8.5±1 cm is the standard that verifies that the gelatin will reproduce the approximate penetration depth seen in living muscle. Shots into standard ordnance gelatin reproduce bullet expansion and fragmentation pattern, bullet penetration depth, temporary cavity size and location, and the yaw behavior of the bullet. Ordnance gelatin, however, is expensive. Preparing it properly and using it correctly are time-consuming and demand great attention to detail.
Shots into water cause bullets to expand as they do in gelatin or muscle.' Water-filled tanks are used almost universally for recovering test bullets in criminalistics laboratories. We have published an article describing a method for shooting into a homemade water tank. 2 In general, however, water tanks are expensive and bulky, and tanks are justified only where a lot of bullet testing is done. In 1990, IWBA member Gus Cotey published an article describing a "poor man's ballistics lab" in which he fired into lined-up water-filled cardboard milk or juice cartons.' More recently, Gus published a follow-up article describing the limitations of water-filled cartons in predicting bullet penetration distance.4 Another recent article, in which water-filled cartons were used to test rifle bullets,' illustrated the inconvenience of having to use up to 16 cartons to assure capturing the test bullet.
In any method of testing bullet performance, recovering the test bullet is mandatory. FMJ rifle bullets have a strong tendency to change their direction of travel considerably when they yaw in water, gelatin, or the human body. This causes a problem in gelatin and in water testing since yawing bullets often exit the sides of the test mediUm and are lost. Hagen had to add more cartons on the sides of his lined-up central cartons to increase the chances of catching the 5.45x39 mm bullet he tested, which acted like an FMJ bullet, yawed and changed its direction of penetration.'
Although soft-point or hollow-point expanding bullets nearly always penetrate in a straight path, in gelatin, water, or living tissue, after they expand, there must be enough tissue simulant to encompass the entire bullet path. Most bullets will penetrate about 1.5 times as far in water as in standard 10% ordnance gelatin: some penetrate even farther. This adds inconvenience by increasing the number of cardboard cartons needed to capture the test bullet. To capture an expanding handgun bullet, that expands, six lined-up cartons should suffice. But the reason for the testing is most often to find out if the bullet expands or not. If the bullet does not expand, twelve lined-up cartons might be needed to capture it.
The purpose of this paper is to describe a simple and inexpensive test of bullet effects, which requires only one carton per shot, in hopes, it will encourage more widespread use of bullet testing.
METHOD
Figure one shows a 26-inch long, 17 inches wide, and nine-inch high-corrugated cardboard box, which has been divided in half, lengthwise, by stapling in place a 1/2-inch fiberboard divider. This produces two eight by nine-inch channels, each 26 inches long. These channels can be divided by corrugated cardboard spacers, from four to seven inches apart, as shown, which are held in place by the unspun cotton fiber material filling the spaces between them.
One Winchester 147 grain hollow-point bullet was fired, from a 9mm Parabellum Browning HiPower handgun, directly into the right-side channel of the cotton-filled box.
Another Winchester 147 hollow-point bullet from the same lot was fired from the same 9mm Parabellum Browning HiPower handgun through a water-filled half-gallon cardboard milk carton placed two inches in front of the right-side channel of the cotton-filled box. That bullet passed through the water-filled carton and then into the cottonfilled box.
For both shots, the box was placed about ten feet from the handgun's muzzle, and the light-sensing screens of an Oehler Model 35 chronograph were placed a few feet in front of the box.
Although not shown in Figure one, the water-filled carton is shot after it is placed in a lightweight plastic bag considerably larger than the carton. This bag helps greatly in controlling the water which, propelled by the force of the temporary cavity, leaves the disrupted carton and spreads water over a six to ten-foot radius without the bag.
RESULTS
The velocity of the bullet that passed directly into the cotton-filled box was 1042 ft/sec. It was recovered, undeformed, after having penetrated 23 inches into the cotton. The undeformed bullet is shown on the left side of Figure two.
The velocity of the bullet that passed through the water-filled carton before entering the cotton-filled box was 997 ft/sec. It was recovered after penetrating 15 inches into the cotton fibers. It had expanded to a diameter of 0.56 inches and had five sharp edges of folded-back copper bullet jacket strips protruding from the bullet's expanded diameter as viewed from front to back. This bullet is shown on the right side of Figure two.
In Figure one, a disrupted half-gallon milk carton, through which the bullet that expanded passed, is shown a few inches in front of the cotton-fiber-filled box.
Previous unreported testing has shown the cotton or polyester material has another advantage that is evident when capturing rifle bullets: when the rifle bullet yaws in this material (as shown by the shape of holes in the spacers, it does not change the direction of its penetration. This makes FMJ rifle bullets far easier to capture in cotton or polyester fiber than they are in gelatin or water, where they do change direction as they yaw. Based on my previous testing, the M193 bullet, fired from an M16A1 rifle, is likely to require seven or eight feet of polyester pillow stuffing to capture it. But since the bullet travels straight, a six-by-six inch channel is probably adequate to capture these rifle bullets -- provided the shots are kept in the center of the channel and the boxes are lined up squarely.
DISCUSSION
The hybrid test method described here combines water, a tissue simulant that causes a bullet to expand as it does in living soft tissue, with cotton, a material used to capture test bullets without deforming them. We know from testing bullets in gelatin that if an expanding-type handgun bullet is going to expand it will do so within a few inches of entry into the gelatin, where its velocity is highest. Thus, the four inches of water in the carton is sufficient to expand any bullet that is, going to expand. After the water, all that is needed is a material to capture the bullet without changing it further. Unspun cotton fibers, by wrapping around the spinning bullet, stop it in a shorter distance than does further penetration into the water. The great advantage of cotton, however, is that it is reusable practically indefinitely. After every few shots, it is useful to repair holes made in the cardboard spacers by previous bullets. These spacers are not essential to the method reported here, but aid in finding the fired bullets rapidly.
It should be noted that unspun cotton fiber is not currently easy to obtain. It appears to have been essentially replaced for padding in clothing, quilts, or comforters, by polyester fiber. I could not
locate uspun cotton fiber in Gainesville, FL, and had to order it over the internet (www.halcyonyam.com). Based on a few comparison shots, it appears that the easier-to-find polyester pillow stuffing can be used interchangeably with cotton as a medium for catching bullets without deforming them.
To estimate the effectiveness of any expanding-type handgun bullet, its expanded diameter, and the depth to which it penetrates must be known. Bullet expansion and penetration are related inversely: for bullets of the same caliber and weight, the larger a bullet's expanded diameter, the shallower its penetration depth. The test described here reveals a bullet's expanded diameter. A bit of experience testing bullets in gelatin, a perusal of some of the wound profiles shown in this issue (pp.25-38) or results from published studies reporting testing of bullets in gelatin, will allow accurate estimation of the penetration depth for a bullet, given its caliber, weight, and expanded diameter.
CONCLUSION
The calibration and standardization of ordnance gelatin was done in the mid-1980s. Since then the quality and reliability of handgun bullets has increased greatly. Outlandish advertising claims become less likely when a reliable test is available to disprove them. But there is still the problem of quality control. From time to time a lot of ordinarily reliable bullets are produced which fail to perform as they should. The more widespread the availability of valid bullet testing, the more likely it is that substandard bullets will have their defects exposed before they can endanger the lives of their users.
The bullet test described here is especially applicable to exposing: unsatisfactory expansion of handgun bullets. This test method is simple and inexpensive enough so that serious users of handgun bullets, whose life might depend upon the reliability of these bullets, can test their own bullets without great inconvenience. This makes the user independent of possibly unreliable tests done by others or by the bullets' manufacturer.
This simple and reliable bullet testing method in the hands of all serious shooters should, over time, increase the overall quality of available bullets.
ACKNOWLEDGEMENT
The basic idea for the hybrid test reported here came from Mr. Merrill Martin, avid shooter
and innovative firearm technology experimenter (and developer of the now widely used molybdenum disulfide bullet coating), of Emeryville, CA. The use of two different materials in the same bullet test is based on a test he described to me. He simulates a small animal with a plastic container, filled with a mud used to lubricate oil drills. He then catches the bullet as it exits in hs ten-foot-long box filled with oiled sawdust. He then finds the bullet using a metal detector. Oiled sawdust is te other material, in addition to unspun cotton fiber, that can be used to catch bullets without deforming them in the process.
References
I . Fackler ML. Police Handgun Ammunition Selection. Wound Ballistics Rev, 1 992; I (3):32-37.
2. Jones RL. Water Testing .38 Special +P Hollow Points. Wo11nd Ballistics Rev 1997;3( I ): 1 3 - 1 6 .
3 . Cotey G. A poor man's ballistics lab. Rifle 1 990; 1 28 : 1 8-2 1 &43.
4. Cotey G. The Limitations of Water-filled Cardboard Cartons in Predicting Bullet Penetration. Wound Ballistics Rev 1 999;4( I ):30-35.
5. Hagen M. 5.45x39 MM JHP Ammunition for the AK-74. Wound Ballistics rev 200 I ;5( I ); 1 7-22.
6. Dahlstrom DB, Powley KD. Comparative Performance of 9mm Parabellum, .38 Special, and .40 Smith & Wesson Ammunition in Ballistic Gelatin. Wound Ballistics Rev 1 996;2(3 ):8-28.
7. Results from bullet testing in 10% Ordnance Gelatin available from the Fireams Training Unit of the FBI Academy, Quantico,
VA (from about 1990 until the present).
8. Mann FW, MD. The Bullet 's Flight from Powder to Target. New York, Munn & Co, 1909. pp 59-60.
