What is GMJ?

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GMJ stands for “gilded metal jacket” and refers to the metal cover or casing for bullets.  Standard bullets typically have softer cores that are made of lead. When a metal casing is used to protect the softer core, the bullets are said to increase their muzzle velocity.  In the case of GMJ, the metal casing or shell being used is one of the gilding metal group.  Gilding metals are typically made of a combination of copper and zinc. The former metal comprises about 90-95% of the metal casing while the latter metal completes the metal jacket at 5%-10%.

For most people, GMJ is just the same or similar with bullets that are classified as FMJ or full metal jackets.  Both types involve the use of metallic casing or alloy combinations in order to improve the muzzle velocity of bullets.  The main difference between full metal jackets and gilded metal jackets is in terms of casing application.  FMJ bullets involve applying the metal casing to the softer lead core.  GMJ bullets meanwhile involve metal or alloy plating directly to the core.  In terms of performance, GMJ and FMJ bullets are also similar.  With similarity in terms of quality and performance, some people prefer GMJ or gilded metal jackets because they are often cheaper when compared with standard FMJ.

Aside from the improvement in muzzle velocities, metal casings in bullets like GMJ also helps to protect the bores from steel or similar materials that are used in the bullet core.  With gilded metal jackets or casing, bullets are also said to behave differently when inside the gun barrels and when used during firing.  Standard and softer bullets have the ability to expand upon impact and this property especially applies to bullets with hollow points or those that have soft tips.  With gilded metal jackets or GMJ, the expansion will be restricted during impact and therefore the firing of the gun will result to smaller holes or wounds.  There is also a greater possibility of the bullet to pierce through a body part because of the metal casing provided by metal-encased bullets like GMJ.

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