Modern air rifles for hunting small game have a smaller CO2 or compressed air reservoir built into the gun. These rifles usually fire .177-, .22-, or .25-caliber small projectiles (pellets).
Big-bore air rifles are designed for hunting larger game. These guns:
- Typically use .357- to .50-caliber ammunition.
- Must have separate pressurized compressed air tanks to fill their large air reservoirs.
- Depending on the weight of the projectile, often can fire multiple shots before you need to refill them with compressed air.
- Usually are bolt-action, single-shot rifles, but some .357-caliber models use a rotating clip that holds several projectiles.