Tannerite

Tannerite is the brand name of a binary explosive marketed primarily for making exploding targets for firearms practice.^[1] It is a patented^[2] combination of ammonium nitrate (an oxidizer) and aluminum powder (a fuel) that is supplied as two separate powders that are mixed and shaken to produce an explosive. 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.^[2] It is also not flammable – an explosion cannot be created by a burning fuse or electricity.^[3] 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.^[4] Other combination explosives are generically referred to as Tannerite.^[4]

Uses

Tannerite is intended to detonate when shot by a high-velocity firearm cartridge. Low-velocity shotgun ammunition will not initiate a detonation.^[2]

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 persons who are firing at long ranges. For such a use, a long-range rifle shooter sets up targets and retreats to a distant firing position. 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 movie-like experiences such as exploding cars.

The manufacturer recommends using no more than 0.5-pound (0.23 kg) of the mixed composition at once, for safety reasons, 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.^[4]

Car hood in flight after 0.5 pounds (0.23 kg) of Tannerite is detonated under the hood.

Form for manufacture and sale

Tannerite is sold in pre-sized quantities for target practice, avalanche control and police use, as well as larger quantities.

Tannerite consists of two components: a catalyst or sensitizer and a bulk material or oxidizer. The oxidizer is a mixture of 85% 200-mesh ammonium nitrate and 0–15% ammonium perchlorate, while the catalyst is a mixture of 90% 600-mesh dark flake aluminium powder, 5% 325-mesh titanium sponge and 5% 200-mesh zirconium hydroxide.^[2] Simpler mixtures of ammonium nitrate and aluminium powder often named as ammonal are also known to work.

With the pre-sized quantities, the company provides non-sparking polyethylene mixing bottles.

Legal restrictions

In the United States, ATF regulations allow the two components to be legally purchased, since neither one is an explosive by itself.^[5] However, the mixture is an explosive once mixed, and cannot be transported in that form without following strict regulations including insurance, packaging, and signage on the vehicle. 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.^[1]

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".^[6][7]

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.^[8] 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.^[9] Previously, only the Hasting's Cutoff BLM land was affected, a popular shooting spot an hour outside of Salt Lake City, UT, 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.^[10][11][12]

Notable incidents

A Minnesotan man was fined $2,583 and sentenced to three years' probation^[13] 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.^[14][15] The blast could be felt at Prairie Island Nuclear Power Plant (roughly 5 miles away).^[16]

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.^[17]

A man was killed by shrapnel at a farm in Fillmore County, Minnesota on June 15, 2013 after Tannerite was shot at a bachelor-bachelorette party after it was placed inside some metal objects. Fillmore County Sheriff Daryl Jensen stated that in this case the Tannerite was “used with other materials” in a manner that was not included in the manufacturer’s recommendations.^[3]

Shrapnel killed a boy and injured a man in Sequoyah County, Oklahoma on February 9, 2015 after a reported two pounds of Tannerite was placed in a stove and shot with a high-powered rifle.^[18]

A 24-year-old man from Portland, Oregon, used a Tannerite explosion as a means of suicide. Officials indicated that on March 19, 2015, the man parked his car along US Route 26 in a rural area near Mt. Hood and walked into nearby woods, where he detonated a "large quantity" of Tannerite with a .223 caliber rifle. The blast shattered trees and resulted in a crater two feet deep and ten feet wide.^[19]

References