The 2020–present United States ammunition shortage refers to a significant and ongoing scarcity of ammunition in the U.S. that began around early 2020 and has continued for several years. Several factors have contributed to this shortage: 1. **COVID-19 Pandemic:** The onset of the pandemic led to increased demand for firearms and ammunition as people sought to protect themselves and their families. This surge in demand coincided with disruptions in manufacturing and supply chains caused by lockdowns and factory closures.

A black powder cartridge is a type of ammunition that uses black powder as its propellant. Black powder, also known as gunpowder, is a mixture of saltpeter (potassium nitrate), charcoal, and sulfur. While black powder was historically the first form of smokeless propellant used in firearms, it has largely been replaced by smokeless powder in modern ammunition due to its higher energy density and efficiency.

Buck and ball is a historical form of ammunition used primarily in smoothbore firearms, particularly during the 18th and early 19th centuries. It consists of a lead ball (usually .69 caliber) and several smaller lead shot (often referred to as "buckshot") packed together in a single cartridge. When fired, the larger ball would travel towards the target with considerable force, while the smaller shot would spread out, increasing the likelihood of hitting multiple targets at close range.

Collaborative Research into Small Arms Technology (CRISAT) typically refers to initiatives or programs that focus on the study and development of small arms and their associated technologies through collaborative efforts among various stakeholders. These stakeholders can include governments, academic institutions, private industry, and non-governmental organizations (NGOs). The objectives of such collaborative research might include: 1. **Innovating Safer Technologies**: Developing new materials or designs that enhance safety in the use of small arms and reduce accidental discharges.

Caseless ammunition is a type of firearm ammunition that does not have a traditional cartridge case. In standard ammunition, the cartridge case serves multiple functions: it holds the primer and propellant, provides structural integrity, and ejects from the firearm after firing. In caseless ammunition, these functions are achieved without a separate case. Instead, caseless ammunition typically consists of a propellant that is chemically designed to contain the projectile and primer within the cartridge itself.

A live fire exercise (LFX) is a military training event in which live ammunition is used to simulate real combat scenarios. These exercises are conducted to train military personnel in the use of weapons and tactics in a realistic environment. Participants may include soldiers, airmen, sailors, and other military forces working together to gain practical experience in firing weapons, coordinating attacks, and executing mission objectives under conditions that closely resemble those of actual combat.

Dense Inert Metal Explosive (DIME) refers to a type of munition that utilizes a combination of dense materials and inert components to create a powerful explosive effect while minimizing the production of hazardous shrapnel and collateral damage. The key characteristics of DIME include: 1. **Dense Materials**: Typically incorporate a heavy metal, such as tungsten or tantalum, which increases the mass of the explosive and enhances its lethality upon detonation.

The term "dud" can have several meanings depending on the context in which it is used: 1. **General Definition**: A "dud" refers to something that fails to work as intended or does not meet expectations. This could apply to a product, event, or situation that is disappointing or underwhelming.

"Match grade" typically refers to ammunition or firearms that are manufactured to a higher standard of precision and quality, designed specifically for use in competitive shooting scenarios. Here are the key characteristics of match-grade products: 1. **Precision Manufacturing**: Match-grade ammunition is produced using tighter tolerances than standard ammunition, resulting in uniform bullet weight, consistent powder charges, and more precisely calibrated dimensions. This helps achieve better accuracy.

Incendiary ammunition is a type of projectile designed to ignite material upon impact. It typically contains a chemical compound or a mechanism that produces intense heat and flames when the bullet strikes a target. This incendiary effect is achieved through materials that can burn or react exothermically, creating fire or explosions. Incendiary rounds are often used in military applications, particularly against flammable targets, equipment, or structures, and can be effective in causing significant damage by igniting fires.

A Multi-Star Signal Cartridge is a type of pyrotechnic device used primarily for signaling, distress signaling, and other applications where a visible or audible signal is necessary. These cartridges are designed to be launched into the air, producing bright flares or colored signals that can be used in various environments, such as maritime, aviation, outdoor activities, and emergency situations.

A Saboted Light Armor Penetrator (SLAP) is a type of ammunition designed to penetrate armor, specifically used in military applications. The term "saboted" refers to the use of a sabot, which is a device that allows a projectile of smaller diameter to be fired from a larger caliber gun. The sabot provides support and guidance to the projectile as it travels down the barrel and into flight.

The Selectable Lightweight Attack Munition (SLAM) is a type of precision-guided weapon system designed for use in military operations. It typically features advanced targeting capabilities, allowing for precise strikes against designated targets while minimizing collateral damage. SLAMs are often characterized by their lightweight design, enabling easier deployment from various platforms, including aircraft, drones, and ground vehicles.

The term "rate of fire" refers to the frequency at which a weapon can discharge rounds, typically measured in rounds per minute (RPM). This term is commonly used in the context of firearms, artillery, and other projectile-launching devices. Rate of fire can be influenced by several factors, including: 1. **Type of Weapon**: Semi-automatic, automatic, and bolt-action rifles have different rates of fire.

Rocket Ball is a game that combines elements of soccer and rocket-powered vehicles, creating a fast-paced, competitive environment. The mechanics typically involve players controlling customizable cars that can jump, boost, and perform aerial maneuvers to hit a large ball into the opposing team's goal, similar to a soccer match. The objective is to score more goals than the opponent within a set time limit.

"Rotation of ammunition" refers to the practice of regularly replacing or cycling through stored ammunition to ensure that it remains in good condition and is effective when needed. This concept is important for both military and civilian firearm owners. Key aspects include: 1. **Shelf Life:** Ammunition can degrade over time due to factors like moisture, temperature fluctuations, and exposure to contaminants. Regularly rotating ammunition helps ensure that older rounds are used before they potentially lose their effectiveness.

Small arms ammunition pressure testing is a method used to measure the pressure generated within a firearm chamber when a round of ammunition is fired. This testing is essential for several reasons: 1. **Safety**: Ensuring that ammunition does not exceed the pressure limits for a specific firearm is critical to prevent dangerous malfunctions, such as ruptured chambers or catastrophic failures that can lead to injury.

Subsonic ammunition refers to cartridges designed to travel at speeds below the speed of sound, which is typically around 1,125 feet per second (fps) at sea level. Since sound speed can vary based on factors like altitude and temperature, the exact threshold for subsonic is typically considered to be around 1,000 fps.

The "Treatise on Ammunition" typically refers to a comprehensive work or manual that discusses various aspects of ammunition, including its types, uses, production, and technical specifications. Such treatises are often aimed at military personnel, arms manufacturers, and researchers interested in ballistics and the science behind munitions.

The Loschmidt constant, often denoted as \( n_0 \), is a physical constant that represents the number density of particles in an ideal gas at standard temperature and pressure (STP). It is named after the Austrian scientist Johann Josef Loschmidt, who calculated the number of particles in a given volume of gas.