Birdshot and buckshot are two distinct types of shotgun ammunition, primarily used for different purposes due to their different projectile compositions and sizes. Here are the key differences between birdshot and buckshot:

Birdshot:

1. Projectile Size: Birdshot consists of multiple small pellets or shot. These pellets are typically quite small, ranging from about .05 to .20 inches (1.3 to 5.1 mm) in diameter. The number of pellets in a load can vary depending on the shotgun shell.

2. Spread: When fired, birdshot pellets spread out rapidly, creating a wide shot pattern. This is advantageous for shooting at flying birds or small game, as it increases the likelihood of hitting the target.

3. Lethality: Birdshot is designed primarily for hunting birds, small game, and clay targets. While it can be lethal at close range, its individual pellets lack the mass and energy to provide effective stopping power for self-defense or against larger animals.

4. Penetration: Birdshot pellets have limited penetration capabilities, especially at longer distances. They are less likely to pass through walls or barriers, making them a safer option in home defense scenarios where overpenetration is a concern.

Buckshot:

1. Projectile Size: Buckshot is loaded with larger pellets, typically ranging from .24 to .36 inches (6.1 to 9.1 mm) in diameter. These pellets are much larger and heavier than birdshot pellets.

2. Spread: While buckshot pellets do spread to some extent, they remain closer together compared to birdshot, especially at longer distances. This makes buckshot more suitable for engaging larger targets at close to moderate ranges.

3. Lethality: Buckshot is designed for personal defense and law enforcement use. The larger and heavier pellets have significant stopping power and are effective against human-sized threats or medium-sized game.

4. Penetration: Buckshot pellets have greater penetration capabilities compared to birdshot. They are more likely to penetrate barriers and can pose a higher risk of overpenetration, which should be considered in self-defense scenarios.

5. Use Cases: Buckshot is commonly used for home defense, law enforcement, and hunting medium-sized game like deer. Birdshot is used for hunting birds, small game, and trap/skeet shooting.

In summary, birdshot and buckshot differ in terms of pellet size, spread, lethality, penetration, and intended use. Birdshot is designed for shooting small, fast-moving targets or clay targets, while buckshot is designed for personal defense and hunting larger game. It's essential to choose the appropriate type of shotgun ammunition based on your intended use and target size.