FULL METAL JACKET BULLET

A 'full metal jacket' (or 'FMJ') is a bullet encased in a copper alloy such as gilding metal, cupronickel, or a steel alloy shell. This shell can extend around all of the bullet or often just the front and sides with the rear left as exposed lead. The jacket allows for higher muzzle velocities than bare lead without depositing significant amounts of metal in the bore. It also prevents damage to bores from steel or armor piercing core materials. This bullet type distinguishes itself from hollow point bullets.

Contents

History

Advantages

Disadvantages

Tumbling and Frangible FMJ Bullets

External links

History

Full metal jacket ammunition is acceptable for military use by the countries that signed the Hague Convention of 1899, which prohibits the use of hollow point or expanding bullets in war between the countries which signed that agreement. It is often incorrectly stated that the prohibition is part of the Geneva Conventions, and that full metal jacket bullets are specifically required. Although the actual language is rather vague, full metal jacket bullets remain the best option available to stay within the letter and the spirit of the Hague convention.
The bullet itself is still highly lethal when fired at close range.

Advantages

★ Because the bullet does not expand as do hunting bullets, FMJ bullets are more effective at piercing armor. Similarly, they better penetrate moderate cover to reach an enemy behind moderate cover, e.g. sheet metal portions of a vehicle.

★ They are more durable and withstand rough handling on the battlefield.

★ Their rounded tips permit proper transit up the feed ramp of a semi-automatic pistol, whereas hollow-point bullets can present greater occasions for jamming; (this risk is reduced by using high-quality firearms and ammunition, and by conscientious gunsmithing).

Disadvantages

Because the bullet does not expand as hunting bullets are designed to, FMJ are much less likely to stop an enemy combatant. Hunters are not allowed to use FMJ rounds, due to their limited stopping power and propensity to travel great distances through brush, buildings, and other cover. The bullet relies on its victim to exsanguinate. FMJ bullets are also less ideal for home defense, as they can easily pierce drywall, unlike hollow points, which are far more likely to expand in the wall and not continue through. This can create a hazardous condition for the home's occupants. Even if an aggressor is hit, it is still possible (especially under the effects of drugs that alter pain perception) that he could continue his assault before losing enough blood to no longer be a threat.
Since they do not expand, arguably a projectile size that would have stopping power in a hollowpoint, would (given the same weight and load, and hence velocity/force) potentially be borderline in an FMJ. As a result there are some armed forces which have since reverted to .45 ACP rather than 9 mm Luger Parabellum chambered sidearms after an initial move to 9mm.

Tumbling and Frangible FMJ Bullets

Some designs of FMJ rifle ammunition inflict more destructive gunshot wounds than others. The secret is in what lies under the metal jacket. Not all FMJ bullets contain a simple lead filling. Here are some examples:

★ Although British Mark 7 .303 ammunition is compliant with the terms of the Hague Convention, it creates more destructive gunshot wounds than standard spitzer bullets due to its internal design. The centre of gravity of the Mark 7 bullet is deliberately shifted towards the rear. This is achieved by constructing the front third of the interior of the bullet from a lighter material such as aluminium or even wood. The result is a tail-heavy FMJ bullet which yaws violently after hitting the target[1].

★ American 5.56mm NATO FMJ ammunition has a much thinner jacket than others. As a result the bullet may yaw and fragment by fracturing along the cannelure.

★ Russian 5.45 x 39mm FMJ ammunition uses a tail-heavy bullet which has a tendency to yaw after hitting the target.

★ German 7.62x51mm NATO FMJ uses a thin steel casing instead of copper, which results in them fracturing after penetration and causing massive tissue damage similar to a larger version of the US 5.56 bullet.

External links

★ Declaration (IV, 3) concerning Expanding Bullets, made at the 1899 International Peace Conference at The Hague, which entered into force on September 4, 1900

★ European Ammunition Box Translations

★ Photos showing terminal effects of British Mark 7 .303 bullets