The frangible bullet at left was struck with a hammer to show the its brittleness. When fired on steel targets, a frangible turns to dust (c.), but in water jugs it acts like an FMJ (r.).

Frangible bullets are brittle bullets, designed to break up on a hard surface. Typically they are "sintered" bullets, usually copper or copper alloy. Sintering is a manufacturing process where you use powdered metal and press it into a shape to form objects. The shapes can then be further treated to make them more solid, dense or tougher.

Typically, the extra work involves heat treatment or hydraulic compression in a mold. The heat or pressure (sometimes both) makes the part harder and denser. When it comes to bullets, the additional heat and pressure are skipped or used very lightly. The idea is to create a bullet tough enough to withstand the forces of loading and feeding but one so fragile that when it strikes a solid object it disintegrates, going back to its powdered state.

Why do this? Bounce-backs and lead exposure. The generally accepted safe distance at which you can shoot a steel plate with lead or jacketed bullets is 10 yards. That's with a properly designed, hard steel plate, in good repair. If you let your cousin Bubba shoot your plates with his .30-30 or slugs, the dents (known in the biz as "craters") will deflect broken bullet parts right back at you.

That's why many ranges get very upset when someone shoots their plates with rifles. Rifle steel is much more expensive, and even so the minimum safe distance for them is 50 to 75 yards. Many rifle instructors won't let you shoot on steel inside of 100 yards.

Also, a lot of ranges are indoors now, and the outdoor range facilities that function as simulators--built to look like houses, etc.--are enclosed.

Unless you live in a McMansion, you won't find many dwellings here in the U.S. that have 10 yards in any direction. And since correct training for indoor uses has to reflect indoor distances, if you are going to build or use a simulator, you have to have engagement distances of a few feet in some instances.

An operation such as Gunsite, with the Funhouse and other simulators, sees a lot of use. If we assume 20 students a class and 20 classes a year, with each student doing the Funhouse twice, that means each target plate will take no fewer than 1,600 hits. With traditional bullets, that's a lot of lead, a lot of bounce-back chances and a lot of lead dust.

Change the bullets to frangibles, and those 1,600 impacts all disintegrate on impact, and there is no lead exposure to the students and instructors.

Now, this is not a win/win situation. There are good reasons lead has been the primary bullet material for centuries. Basically, it comes down to density and durability.

For the same caliber and shape, a frangible bullet will weigh less than that of a similar lead or jacketed bullet. The example I have in front of me, a Speer/LE .40 caliber, weighs only 125 grains--despite being the the same size as a jacketed 180-grain .40 S&W bullet.

The lighter weight complicates loading data, as the loaded round has to feed and function properly in a pistol designed to shoot 180-grain bullets. The weight difference also can change point of impact. However, that isn't as big a problem, since we're planning on using these puppies at two to 10 feet anyway, and the disparity in point of impact, at 10 feet, is almost unmeasurable.

The accuracy of frangibles can also be less, but again, we're shooting at targets across a large room.