Tannerite is the brand name of a patented exploding target used for firearms practice, sold in kit form and containing the components of a binary explosive. The explosive comprises a combination of ammonium nitrate and/or ammonium perchlorate (oxidizers), and a fuel - primarily aluminum powder - that is supplied as two separate powders that are mixed by the user. The combination is relatively stable when subjected to forces less severe than a high-velocity bullet impact, such as a hammer blow, being dropped, or impact from a low-velocity bullet or shotgun blast. It is also not flammable – an explosion cannot be created by a burning fuse or electricity.
Because it is sold as two separate powders, it can be transported and sold in many places without the legal restrictions that would otherwise apply to explosives. The target system as a whole is the patented, trademarked product called Tannerite, although the term is often used to refer to the explosive mixture itself, and other combination explosives are often generically referred to as tannerite.
Tannerite detonations occur at a very high velocity, producing a large explosion and cloud. It is marketed as a target designator that is useful for long range target practice: the shooter does not need to walk down-range to see if the target has been hit, as the Tannerite will detonate and serve as a highly visible indicator.
Tannerite is also used for dramatic effect to provide explosions in weaponry demonstrations or other events. Ordinarily, firing rifle-caliber ammunition will not produce much more than a shattered target or hole (and the sound of the firing) when shot at a target. Using exploding targets can provide cinematic effects such as exploding cars.
For safety reasons, Tannerite recommends using no more than 2 pounds (0.91 kg) of the mixed composition at once, although this guideline is not always followed, and the product can be readily purchased in larger amounts. It is sometimes sold by the pound, and demonstrations of the effects of using up to 100 lb (45 kg) at a time have become popular as internet videos.
Form for manufacture and sale
Tannerite is sold in pre-sized quantities for target practice, avalanche control and police use. Pre-sized quantities are sold with non-sparking polyethylene mixing bottles. Tannerite consists of two components: a fuel mixed with a catalyst or sensitizer, and a bulk material or oxidizer. The fuel/catalyst mixture is 90% 600-mesh dark flake aluminum powder, combined with the catalyst which is a mixture of 5% 325-mesh titanium sponge and 5% 200-mesh zirconium hydride (with an earlier patent listing 5% zirconium hydroxide). The oxidizer is a mixture of 85% 200-mesh ammonium nitrate and 15% ammonium perchlorate.
Simpler mixtures of ammonium nitrate and aluminium powder often named as ammonal are known to be used as do-it-yourself substitutes for Tannerite. Ammonal is made commercially as a substitute for dynamite in blasting. Such homebrew "tannerite"s have unknown standards of quality and safety.
United States law
In the United States, ATF regulations allow the two components to be legally purchased, since neither one is an explosive by itself. ATF advises: "Persons manufacturing explosives for their own personal, non-business use only (e.g., personal target practice) are not required to have a Federal explosives license or permit." A prohibited person (a person barred by federal law from buying or owning a firearm) cannot legally possess mixed explosives. Explosives for lawful target practice must be used once mixed: any transport, storage or commercial use of mixed explosives falls under federal explosives laws, and cannot be transported in mixed form without following strict regulations including insurance, packaging, signage on the transport vehicle, storage magazines, etc.
Various regulations also govern the storage of unmixed Tannerite. As oxidizers and combustibles, the unmixed components still have some shipping restrictions in the United States.
A Maryland law intended specifically to ban the sale or ownership of Tannerite became effective on October 1, 2012, and expanded the definition of an explosive to include, in addition to "bombs and destructive devices designed to operate by chemical, mechanical, or explosive action", "two or more components that are advertised and sold together with instructions on how to combine the components to create an explosive".
On August 5, 2013, the United States Forest Service (USFS) and the U.S. Attorney's office in Denver announced that the USFS is implementing a closure order to prohibit the use of unpermitted explosives, particularly exploding targets using tannerite, on all USFS lands in the Rocky Mountain Region. This region includes national forests and grasslands in the states of Colorado, Wyoming, Kansas, Nebraska, and South Dakota. According to the USFS, at least 16 wildfires in the Western states had been associated with exploding targets. It cost more than $33 million to extinguish the fires. Such a ban has already been implemented by the USFS in Washington, Oregon and Montana. The Bureau of Land Management has banned the use of all exploding targets on BLM land in Utah.
Previously, only the Hasting's Cutoff BLM land was affected, a popular shooting spot an hour outside of Salt Lake City, Utah, which had become abused with the regular use of Tannerite and other explosives. The Bureau of Land Management was also reported to be preparing a Fire Prevention Order that would ban exploding targets on BLM-administered land in the state of Colorado. In 2016, the Bureau of Land Management officially proposed supplementary rules to "restrict the possession, discharge, or use of exploding targets on public land in Colorado."
A Minnesota man was fined $2,583 and sentenced to three years' probation on charges of detonating an explosive device and unlawful possession of components for explosives after he detonated 100 lb (45 kg) of Tannerite inside the bed of a dump truck by shooting it with a rifle chambered in .50 BMG from 300 yards (270 m) away on January 14, 2008, in Red Wing, Minnesota. The man was on probation when he mixed and shot the Tannerite and was not allowed to possess firearms or explosives. The blast could be felt at Prairie Island Nuclear Power Plant (roughly 5 miles away).
A 20-year-old man in Busti, New York shot 18 lb (8.2 kg) of Tannerite on January 13, 2013, that sent a particularly "loud boom" through much of southern Chautauqua County, New York and extending as far south as Pennsylvania, at least 3 miles away. Multiple other sounds of explosions were also reported in the incident. The explosive noise caused numerous phone calls to the Chautauqua County Sheriff's Office, the New York State Police, and other law enforcement in the area.
The September 2016 New York and New Jersey bombings involved improvised explosive devices that contained "a compound similar to a commercial explosive known as Tannerite", set off by a small charge of unstable hexamethylene triperoxide diamine, which served as a detonator for the highly stable ammonal-type secondary charge.
On April 23, 2017, an off-duty U.S. Border Patrol agent, who was shooting at Tannerite targets on state trust land south of Tucson, Arizona, accidentally ignited nearby dry brush, setting off the 46,000-acre Sawmill Fire. At the time, winds were gusting up to 40 miles an hour and the National Weather Service had issued a fire watch in the area. By the time the wildfire was mostly contained one week later, it had jumped over the Santa Rita Mountains and crossed Arizona Highway 83, spreading into the historic Empire Ranch and the surrounding 42,000-acre Las Cienegas National Conservation Area. The estimated cost to fight the blaze was at least $5 million.