Brass knuckles, despite the simplicity of design, is a very dangerous weapon, a strong blow with brass knuckles can break a person's skull quickly and easily. Due to this, the carrying and trade of these items is prohibited by various laws: United States (Washington D.C., California, Illinois, Massachusetts, Michigan, New York and Rhode Island), Austria, Sweden, Germany, Spain, Colombia, Mexico and Guatemala, among others.
Gunsmiths believe that it is weight that determines the strength and power of crushing something with brass knuckles. It turned out that one hundred and fifty grams is the minimum weight for using this weapon to crush objects.
Designed to preserve and concentrate a punch's force by directing it toward a harder and smaller contact area, they result in increased tissue disruption, including an increased likelihood of fracturing the intended target's bones on impact. The extended and rounded palm grip also spreads the counter-force across the attacker's palm, which would otherwise have been absorbed primarily by the attacker's fingers. This reduces the likelihood of damage to the attacker's fingers. It also allows its user to break glass windows without injuring their hands.
Brass knuckles or brass knuckles have been used around the world since ancient times. In India they were used in the fighting technique Vajra mushti, which has been handed down from the Manasollasa since the 12th century.
During the Civil War (1861-1865), brass knuckles made of cast iron, brass, lead and wood were common in the United States. Soldiers bought cast iron or brass ones. If they couldn't or didn't want to afford them, they carved their own out of wood or sand-cast brass knuckles from melted lead bullets.
By the Second World War, brass knuckles and knuckle-duster knives were quite popular with both American and British soldiers. Model 1918 trench knives were reissued to American paratroopers. British commandos even had their own "Death's Head" knuckles with a skull-shaped brass handle.