Ammunition Specifications Gauge: 20 Gauge Shell Length: 2 3/4 in. Slug Weight: 328 gr Slug Type: Rifled Slug Muzzle Velocity: 1600 fps Quantity/box: 5 Rounds per Box This line offers you a full complement of rifled slugs for just about every shotgun gauge. If you shoot with a 410, 20, 16, 12 or 10-gauge, you ll find a slug for your smoothbore here. Remember, rifled slug means the slug is rifled, not your barrel.