Frangible, or "soft," rounds are designed to break apart when they hit walls or other hard surfaces to prevent ricochets during close-quarters combat. Frangible ammunition represents the first viable revolutionary change to firearms science in the past 100 years. Frangible ammunition is a relatively recent development in bullets, presenting a departure from the standard projectiles in use for both range shooting and personal protection. With the advent of modern hostage rescue tactics in the 1970s and 1980s, the military and police agencies began to look for ways to minimize overpenetration risks. One widely-accepted solution was the frangible round, also known as the AET (Advanced Energy Transfer) round.
Frangible rounds are available in a wide array of pistol calibers, but due to the inherently high velocities of rifle rounds, frangible ammunition is much less effective in rifles. It is only produced in 5.56mm NATO and 7.62mm NATO, and its performance in actual combat is dubious. There are two frangible rounds that have been approved for training purposes only. One is a 9mm, and the other a 5.56. Approval for operational use will depend on the special mission requirements (the military necessity) for the round.
Frangible bullets are not made from a lead projectile covered with a copper jacket, but are composites of hybrid materials either pressed together at high pressure or glued together with adhesives. Frangible bullets are designed to break up into smaller pieces upon contact with harder objects or surfaces. The polymer-compound round produces no splashback and vastly decreased ricochets.
Frangible bullets will break up into small, less harmful, pieces upon contact with anything harder than they are. This maximizes the round's transfer of energy to the object and minimizes the chances that pieces of the bullet will exit the object at dangerous velocities. Each of the small fragments quickly loses any energy and therefore pose very little danger to any secondary targets. This means that full-power frangible bullets can be shot at target all the way up to muzzle contact without any worries that the bullet or case will ricochet and potentially hurt either the shooter or others.
Frangible rounds come in a variety of configurations, all of which perform in the same basic manner. Some, like the well-publicized Glaser Safety Slug, are hollowpoint rounds that are filled with tiny metal beads. Others are simply solid rounds with grooves or notches intended to facilitate rapid expansion and breakup.
Frangible bullets have been designed for a number of applications. Frangible bullets are primarily used in training exercises to reduce lead hazards on firing ranges. Frangible ammo is ideal for marksmanship training for both indoor and outdoor ranges, tactical team training, close-in engagement of metal targets and specialized service use. As such, it is the safest full-power training ammo for police and military shooters, civilian range owners and casual shooters.
Glaser Safety Slug, Inc. developed the first frangible bullet in 1974 to provide reduced ricochet and over-penetration danger with improved stopping power over conventional bullets. In 1987, Glaser developed the round-nose frangible bullet offering guaranteed feeding reliability. In 1988 Glaser introduced the compressed-core bullet to maximize bullet weight and the number of bullet fragments. This precision formed bullet also produces target grade accuracy, seldom found in a personal defense bullet. In 1994 Glaser improved fragmentation reliability to below 1,000 feet per second through the use of soft, rather than hard plastic in the bullet tip.
The Interagency Working Group for Non-Toxic Small Arms Ammunition, also known as the "Green Bullet" team, initially focused on non-lead bullet material composed of tin and tungsten is the leading candidate for use in military ammunition. Tens of thousands of rounds have been tested by the military with exceptional results. The armed forces use between 300 million and 400 million rounds of small-caliber ammunition each year. The first 1 million green 5.56-mm bullets will be used in the Army's M-16 infantry rifles. Officials hope to get all the lead out of bullets used in all the services by 2003.
Concerns with over penetration / ricochet hazards aboard aircraft, ships and (e. g.) nuclear power plants that might release hazardous materials have led to efforts to provide small caliber ammunition with reduced ricochet, limited penetration (RRLP) for use by SOF to reduce risk to friendly forces and innocent persons. There are three general levels of frangible: Training [may be used for training only]; reduced ricochet, limited penetration[RRLP, designed for purposes stated]; and general purpose frangible [though no military requirement has been established for a general purpose round for use by conventional forces]. Specific ammunition must undergo wound ballistics testing/ legal review once developed. It can be used for: Close Quarter Battle (CQB); Military operation in Urban Terrain (MOUT); Visit Board Search and Seizure; and Counter-Narcotics (CN) Operation.
Frangible bullets are not armor piercing munitions. In fact, they are the exact opposite. Frangible bullets may represent an unconventional threat to personal body armor, when contrasted with traditional lead based bullets. The true scope and relevance of this threat was not known as of November 2002. At the request of the National Institute of Justice (NIJ), staff of the Office of Law Enforcement Standards (OLES), located at the National Institute of Standards and Technology (NIST), has conducted a limited series of tests evaluating the performance of frangible ammunition against body armor. This preliminary study was designed to attempt to establish the validity of claims that these types of rounds pose a potential safety threat to personal body armor.
The firing of small arms ammunition for training, sport, law enforcement, and military purposes is a major source of environmental pollution. The lead from shot and bullets is a significant environmental and health problem at numerous public, private, and government-operated shooting ranges. Many sites are contaminated with hundreds of tons of lead, the result of years of shooting and target practice. Lead is tainting grounds and water, and is being ingested by wildlife, and has thus become a serious threat to the health and safety of human and animal populations. Indoor ranges pose other serious concerns such as increased lead exposure to the shooter due to the enclosed space and the subsequent need for high capacity ventilation and air filtration systems. Handling of ammunition and contaminated weapons can also produce elevated lead levels in the blood by absorption through the skin.
A non-toxic, all-metal replacement for lead in bullets has been developed at the Department of Energy's Oak Ridge National Laboratory (ORNL). Powder metallurgy techniques have been used to produce metal-matrix composite simulants that have properties very similar to those of lead. Bullets are fabricated from mixtures of powdered metals that are simply pressed at room temperature to produce a high-density material. No heat treating or sintering is necessary to achieve densities and mechanical properties that mimic those of lead and its alloys. Mechanical interlocking and "cold welding" bond the metals together, and can be varied to control the properties of the lead replacement. Bullets can be pressed directly to shape, or "slugs" can be produced that can be swaged into projectiles, with or without jacketing.
Non-lead bullets fabricated employing powder metallurgy simulants have proven to be one-to-one replacements for their lead analogs. Ammunition has been assembled using non-lead bullets and propellant charges matching currently available products. Velocity and chamber pressures were found to be similar to those for the lead-containing projectiles. Accuracy has also been examined and, in many cases, is improved through the use of the non-lead material.
The use of powder metallurgy provides greater flexibility in controlling bullets' properties. Processing conditions, composition, and powder particle size can be used to alter density and impact behavior. The latter is of significant importance in situations where penetration, ricochet, and collateral damage are concerns. The properties of non-lead materials can be controlled so that a bullet fragments into small particles upon impacting a hard target, but remains intact when engaging a soft target. A "frangible" bullet is desirable for close-quarters training, and extends response team capabilities in specialized environments. In addition, the density of the material can be varied over a broad range, allowing for new designs and improvements in ballistic performance.
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