Bullets can be compared to each other for penetration and expansion in water by using a "Fackler" Box. There is a formula to convert the penetration in water to penetration in gelatin.
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.
The box can be made of plywood or 1-inch pine and should be high and wide enough for Zip-loc bags and at least four feet long. The front panel should have a hole large enough to shoot through, but not so large that the water-filled bags fall out.
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.
Bullets can be compared to each other for penetration and expansion in water by using a “Fackler” Box. There is a formula to convert the penetration in water to penetration in gelatin.
Zip-loc bags filled with water are simply lined up in the box.
I have used a Fackler box extensively for several years and have found that the number of bags needed to stop a bullet vary considerably. I’ve had as little as one bag stop an expanding .380 ACP, while it may take several feet of water-filled bags to stop a FMJ bullet fired from the same gun. As for rifles, a Fackler box is not a very practical way of recovering rifle bullets. My experience is that the hydraulic force created by the bullet entering the water at supersonic velocity almost always blows out the sides of the box.
Mayer began his outdoor industry career in 1993 on the NRA Technical Staff where he became American Rifleman magazine first Shooting Editor. Mayer left NRA and entered the business end of publishing in 2003 as Advertising Account Executive for Safari Club International SAFARI Magazine and Safari Times newspaper. In 2006, Mayer was named Publisher of Shooting Times magazine where he was also tasked with launching and leading Personal Defense TV, the first television show of its kind.
In 2008, Mayer returned to the editorial side of publishing, this time in the digital field, as Editorial Director for Guns & Ammo, Shooting Times, Handguns and Rifleshooter online magazines. After a brief stint in 2011 as the Digital Media Director for an ABC TV affiliate, Mayer returned to the outdoors industry and Safari Club International where he is currently Assistant Publisher and Multi-Media Communications Editor.