Definition

Noun: 1. A type of bullet: A full metal jacket is a bullet where the soft lead core is completely encased in a harder metal shell, typically copper or a copper alloy. This jacket prevents the bullet from expanding upon impact.

Usage

• The term is used specifically in the context of firearms, ammunition, and ballistics.
• It describes the physical construction of a bullet, distinguishing it from other types like hollow-point or soft-point bullets.
• It is often abbreviated as FMJ.

Examples

• "Standard military ammunition typically uses full metal jacket rounds."
• "For target practice, FMJ bullets are preferred because they are less expensive and cause less wear on the gun barrel."
• "The forensic report identified the round as a 9mm full metal jacket."

Advanced Usage / Notes

• Legal and Practical Context: Full metal jacket bullets are commonly used by militaries worldwide, as their design often complies with the Hague Convention of 1899, which prohibits bullets that expand or flatten easily in the human body. They are also popular for target shooting and training due to their reliability and cost.
• Terminology Clarification: The "jacket" refers only to the harder metal casing. The phrase "full metal jacket" is a technical description and should not be confused with general slang for being heavily armed or armored, though such usage is derived from this original meaning.

Variants and Related Words

• FMJ: The standard abbreviation for "full metal jacket."
• Jacketed bullet: A more general term for any bullet with a metal jacket, which may not be a "full" jacket (e.g., a bullet with an exposed lead tip is a "soft-point" or "jacketed soft-point").
• Ball ammunition: A military term often used synonymously with full metal jacket ammunition, especially in rifle calibers.

Synonyms

• FMJ bullet
• Jacketed bullet (though this is a broader category)
• Ball round (military context)

Antonyms / Contrasting Terms

• Hollow-point bullet: A bullet designed to expand upon impact for greater stopping power, commonly used in law enforcement and self-defense.
• Soft-point bullet: A jacketed bullet with an exposed lead tip, designed for controlled expansion.
• Lead round nose: A bullet made entirely of soft lead with no metal jacket.

Noun

1. a lead bullet that is covered with a jacket of a harder metal (usually copper)