The question "How big is a 5.56 round?" isn't as straightforward as it seems. The size isn't just about the bullet itself; it encompasses the entire cartridge, including the case, primer, and propellant. Let's break down the dimensions, weight, and compare it to other common calibers.
Dimensions of a 5.56x45mm NATO Cartridge
The 5.56x45mm NATO round, commonly used in AR-15 style rifles, isn't a simple measurement. Here's a breakdown of its key dimensions:
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Overall Length: Approximately 1.97 inches (50mm). This is the total length of the cartridge from the tip of the bullet to the base of the casing. Slight variations exist depending on the bullet type and manufacturer.
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Case Length: Approximately 1.73 inches (44mm). This refers to the length of the brass casing that holds the powder and primer.
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Bullet Diameter: .224 inches (5.56mm). This is the diameter of the projectile itself. It's crucial to note that this is significantly smaller than the case diameter.
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Case Diameter: Approximately .45 inches (11.5mm). This is the widest part of the cartridge casing.
These dimensions are approximate, as slight variations can occur depending on the manufacturer and specific ammunition load.
Weight of a 5.56x45mm NATO Round
The weight of a 5.56 round is also variable, largely determined by the bullet weight. Common bullet weights range from 55 grains to 77 grains. The entire cartridge's weight will be slightly higher, accounting for the casing, primer, and propellant. A typical 55-grain 5.56 round might weigh approximately 4.1 grams (63 grains), while a 77-grain round could weigh around 5 grams (77 grains). It's essential to consult the manufacturer's specifications for precise weight information.
5.56 vs. Other Calibers: A Size Comparison
Understanding the size of the 5.56 round often involves comparing it to other commonly used calibers:
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.223 Remington: While often used interchangeably, the .223 Remington and 5.56x45mm NATO are not exactly the same. The .223 Remington has a slightly lower chamber pressure, meaning a 5.56 round can be safely fired from a .223 chamber, but not necessarily vice-versa. The overall dimensions are very similar.
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7.62x39mm: This round, commonly used in AK-47 rifles, is significantly larger and heavier than the 5.56x45mm. It possesses greater stopping power but less range and accuracy.
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9mm: The 9mm pistol round is considerably smaller and shorter than the 5.56, designed for handguns rather than rifles.
Conclusion: Context is Key
The "size" of a 5.56 round is multifaceted and depends on the specific aspect being measured. Considering the overall cartridge length, bullet diameter, weight, and comparing it to other calibers provides a more complete understanding. Always consult the manufacturer's specifications for precise details. Remember safety precautions when handling ammunition.
